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Geological  and  Solar  Climates 


Their  Causes  and  Variations. 


A    THESIS. 


BY 

MARSDEN     \IANSON,    C-    ED 


Geology  and  Physics: 
UNIVERSITY    OF    CALIFORNIA, 

May,    1893. 


Entered  according  to  Act  of  Congress  in  the  year  1893, 

BY  MARSDEN  MANSON, 
In  the  office  of  the  Librarian  of  Congress,  at  Washington,  D.  C. 

V 


SAN  FRANCISCO: 

George  Spaulding  &  Co.,  Printers. 

414  Clay  Street. 


ERRATA. 

Preface,  next  line  to  last,  for  ivaiver  read  waver.  • 

Page  5,  foot-note,  7th  line  from  bottom,  for  Helvetic  <- 
read  Helvetic. 

Page  14,   in   foot-note,    6th   line   from  top,  for  Zeno- ^ 
graphic  read  Zenographical. 

Page  17,  last  line,  for  area  read  era.  ~~ 

Page  20,  14th  line  from  top,  for  wherever  read  whenever.  *^ 

Page  23,  3d  line  from  bottom,  for  area  read  era.  ^ 

Page    23,    4th    line  , fro  in    bottom,    for    merging    read-' 
emerging. 

Page  41,   15th   line  from  top,  after  necessary  for  the,  ^ 
insert,  removal  of  glacial  conditions,  and  for  the 

Page  44,  the  second  paragraph  should  read:  The 
trapping  process  not  being  a  function  of  the  orbital  dis- 
tance, nor  of  the  actual  amount  of  heat  received,  but 
of  the  composition  of  the  atmosphere,  this  rise,  etc. 

Page  47th,  6th  line  from  top,  insert  "  at  end  of  para-  «-" 
graph,  after  out. 

Ib,  6th  line  from  bottom,  for  *  substitute  f.  *- 


PREFACE. 


The  worshipers  of  truth  are  delving  in  every  ham- 
let— many  have  before  them  the  daily  burdens  of  life, 
from  which  they  can  snatch  but  a  few  hours  each  day  to 
give  to  their  chosen  faith. 

Every  now  and  then  one  comes  forward  with  some 
skillfully  carved  jewel  which  he  has  wrought  into  shape 
to  deck  his  shrine.  Sometimes  it  is  only  a  little  piece 
merely  good  for  inlaying  the  walls,  yet  it  fits  well  in  its 
place  and  strengthens  the  faith  of  other  workers.  Again 
it  is  the  great  keystone  for  some  massive  arch  whose  other 
stones  were  laid  in  bygone  times.  Yet  again  it  is  a 
mighty  truth  that  will  not  fit  in  the  great  building 
at  all  until  the  wrong  work  be  torn  down,  and  then  it 
forms  the  base  for  one  of  the  steadfast  and  everlasting 
towers.  So  pure  must  be  the  faith  of  those  who  bow 
at  the  hallowed  shrines  of  truth  that  they  would  tear 
down  these  shrines  rather  than  let  them  stand  upon,  or 
even  harbor  error. 

The  writer  gives  in  this  little  book  a  keystone  which 
he  knows  will  not  fit  in  the  present  building  unless 
some  errors  be  torn  out.  Those  whose  faith  is  true 
will  not  wajfver  nor  come  grudgingly  to  the  work  of  re- 
building. 


>   OP 


GEOLOGICAL    AND    SOLAR    CLIMATES, 
THEIR  CAUSES  AND  VARIATIONS. 


THE  CAUSE  OF  THE  ICE  AGE. 

' (  The  most  important  problem  in  terrestrial  physics  *  * 
and  the  one  which  will  ultimately  prove  the  most  far  reach- 
ing in  its  consequences,  is:  What  are  the  physical  causes 
which  led  to  the  Glacial  Epoch  and  to  all  those  great  secular 
changes  of  climate  which  are  known  to  have  taken  place 
during  Geological  Ages?"  (Dr.  Croll,  Climate  and  Cos- 
mology.) 

"An  attentive  study  of  the  physical  Geography  of  the 
earth  and  its  influences  on  Climate,  together  with  a 
judicious  application  of  the  simplest  physical  theories,  will 
enable  us  to  gain  by  and  by  a  better  knowledge  of  Geologi- 
cal climates."  (Prof.  A.  Woeikof,  Nature,  March  2, 
1882,  p.  426.; 

Since  Agassiz  announced*  the  past  existence  of  an 
age  during  which  ice  covered  temperate  and  tropical 
land  areas,  the  cause  of  this  wonderful  phenomenon  has 
been  a  problem  of  profound  interest.  Upon  the  cor- 
rect solution  of  it  hinges  also  the  cause  of  Geological 
climates. 

*In  1821  Venetz  called  attention  to  the  once  greater  extension  of  Glaciers; 
and  in  1824  Prof.  Esmark  made  similar  observations  as  to  the  Glaciers  of 
Norway.  Phil.  Mag.,  Vol.  XXVII,  p.  321. 

As  early  as  1821  a  prize  of  300  livres  was  offered  by  the  He^ivitic  Soc.  of 
Nat.  Sci.  for  the  collection  of  facts  regarding  the  increase  or  decrease  of 
the  extension  of  glaciers  in  the  Alps.  Tillock's  Phil.  Mag.,  Vol.  LV1I,  p 
307. 

But  to  Agassiz  belongs  the  honor  of  having  first  pointed  out  the  exist- 
ence of  the,  Ice  Age  wnen  all  glaciers  were  vastly  more  extended  than  at 
present. 


6  GEOLOGICAL    AND    SOLAR    CLIMATES, 

So  great  has  been  the  interest  attaching  to  this  sub- 
ject, that  more  study  has  been  devoted  to  it  during  the 
past  fifty  years  than  perhaps  to  any  other  in  Geology; 
hardly  a  leading  scientific  magazine  runs  through  a 
year's  numbers  without  one  or  more  articles  upon  it; 
and  no  Geological  Society  is  without  zealous  students  of 
glacial  phenomena.  Some  have  become  so  absorbed  in 
the  subject  that,  led  by  the  recurrence  of  certain  slight 
astronomical  influences,  they  recognize  a  glacial  period 
for  slight  and  widely  scattered  evidences  of  possible 
early  local  glaciation,  forgetful  of  the  fact  that  an  era  of 
frigid  climate  could  not  intervene  between  two  eras  of 
tropical  climates  without  the  intervention  of  eras  of  tem- 
perate climates. 

The  evidences  establishing  the  reality  of  the  Ice  Age* 
during  the  Quaternary  period  are  now  beyond  dispute. 
It  is  difficult,  however,  to  establish  by  geological  evidence 
the  synchronal  glaciation  of  all  the  continental  areas 
known  to  have  been  heavily  glaciated.  This  difficulty 
arises  from  the  fact  that  the  identity  of  various  strata 
has  to  be  established  by  fossils  of  varying  conditions 
and  characters;  it  is  also  rare  that  the  same  geologist 
has  visited  and  compared  the  evidence  upon  more  than 
two  continents,  thus  eliminating  probable  errors  from 
unequal  subaerial  denudation  and  exposure  in  the  differ- 
ent zones  of  present  climates  and  upon  different  conti- 
nents. Again,  the  proof  of  the  contemporaneous  existence 
of  corresponding  strata  upon  different  continents  in  the 
same  latitude  is  sometimes  attempted  by  a  comparison 

*  The  writer  prefers  the  nomenclature  of  Dr.  Geikie  and  others  using  the 
term  Ice  Age  rather  than  Glacial  Epoch,  or  Period.  The  duration  of  this 
age  was  not  recorded  in  the  same  manner  and  terms  as  either  previous  or 
succeeding  ages;  this  is  due  to  the  inactivity,  or  even  absolute  suspension 
of  the  great  forces,  heat  and  moisture,  over  continental  areas  during  this 
age;  under  estimates  of  its  duration  are  thus  liable  to  be  made. 


THEIR    CAUSES    AND    VARIATIONS.  7 

of  land  fauna  and  flora,  with  marine  fauna  and  flora,  or 
even  by  more  complex  comparisons.  Fossil  plant  life  is 
by  far  more  reliable  than  animal  life  for  comparative 
purposes. 

Another  misleading  factor  is  found  in  the  interpreta- 
tion of  the  great  trans-continental  lines  of  terminal 
moraines  into  the  absolute  limits  of  glaciation.  Con- 
sidering the  great  lapse  of  time  since  the  removal  of 
glacial  conditions  in  temperate  and  tropical  latitudes,  it 
is  more  than  probable  that  the  existing  unobliterated 
evidences  by  no  means  mark  the  extreme  limits  of  a 
lighter  and  more  extended  glaciation  whose  traces  have 
been  destroyed,  but  which  can  justly  be  interpolated 
between  the  existing  very  marked  traces  of  enormous 
glacial  extension  during  Quaternary  times.  It  is  not 
impossible,  nor  entirely  improbable,  that  early  local 
glaciation  did  not  occurv  during  the  early  part  of  the 
Cenozoic  Era,  or  even  earlier,  but  the  data  upon  which 
to  establish  the  occurrence  of  such  early  local  glaciation 
are  both  meagre  and  obscure.  Should  the  evidences  of 
such  early  local  glaciation  be  developed  beyond  dispute, 
they  will  in  no  way  interfere  with  the  interpretation  to  be 
given,  but  they  will  strongly  corroborate  certain  portions 
of  this  interpretation.  So  far  as  the  author  has  been 
able  to  examine  such  evidence,  it  has  been  found  to  be 
between  strata  containing  fossil  life  of  a  torrid  character, 
with  no  evidences  of  a  gradual  merging  into  a  temperate 
climate  above  and  below  it,  as  in  Quaternary  glaciation.* 

Before  entering  further  into  this  discussion,  it  may  not 
be  out  of  place  to  briefly  review  the  principal  theories 
advanced  to  account  for  the  Ice  Age.  It  will  be  seen 
that  physicists  and  astronomers  have  vied  with  geolo- 

*  This  question  is  so  important  and  has  so  broad  a  bearing  that  it  will 
be  reverted  to  later  under  the  heading  Palaeozoic  Glaciation. 


8  GEOLOGICAL  AND  SOLAR  CLIMATES, 

gists  in  the  diligence  of  the  search  for  the  cause  of  this 
age,  and  their  minds  have  been  as  fertile  in  the  number 
of  causes  assigned  as  the  true  one.  Not  one  of  all  the 
causes  suggested  has  been  sustained  by  argument  without 
a  flaw  in  the  reasoning,  and  110  demonstration  has  been 
made  which  has  carried  conviction  to  the  scientific  world. 

It  would  not  be  instructive  to  attempt  to  review  all  of 
the  theories  which  have  been  urged.  The  tendency  to 
ascribe  remote  inadequate  or  obscure  causes,  rather  than 
to  interpret  facts  and  phenomena  in  accordance  with 
known  laws,  is  apparent  in  many.  Some  writers  have 
ascribed  causes  resting  only  upon  hypotheses  beyond  the 
range  of  either  analysis  or  investigation;  such  hypotheses 
can  only  stand  in  the  absence  or  failure  of  all  other 
assignable  causes.  Therefore  the  leading  causes  only 
will  be  briefly  mentioned. 

In  a  recent  monograph  on  the  subject,  the  following 
are  given  :* 

1.  A  decrease  in  the  original  heat  of  the  globe. 

2.  Changes  in  the  elevation  of  land,  and  consequent 
variations  in  the  distribution  of  land  and  water. 

3.  Changes  in  the  obliquity  of  the  axis  of  the  earth. 

4.  A  period  of  greater  moisture  in  the   atmosphere. 

5.  Variations  in  the  amount  of  heat  radiated  by  the 
sun. 

*  Transactions  of  the  Technical  Society  of  the  Pacific  Coast,  Sept.,  1891, 
Vol.  VIII.  See  also  The  Climate  Controversy,  S.  V.  Wood,  Jr.,  Geol.  Mag., 
1876  and  1883.  Climate  and  Time,  Climate  and  Cosmology,  Croll.  Island 
Life,  Alfred  Russell  Wallace,  F.  K.  S.,  etc.  Philosophical  Magazine,  May, 
1864.  British  Association  Keports,  part  2,  p.  11.  Proceedings  Royal 
Soc.,  vol.  xxviii,  p.  15.  Quart.  Jour.  Geological  Soc.,  Feb.,  1878.  Nature, 
July  4,  1878.  Trans.  Geological  Soc.,  Glasgow,  Feb.  22,  1877.  The  Ice 
Age  in  North  America,  Dr.  Fred.  G.  Wright,  Appendix  by  Warren  Upharn. 
The  Cause  of  an  Ice  Age,  Sir  Robert  Ball,  F.  R.  S.,  etc.  Revolutions  de 
la  Mer.  Deluges  Periodique,  Alphonse  Joseph  Adhemar. 


THEIR    CAUSES    AND    VARIATIONS.  9 

6.  A  variation  in   the  heat  absorbing  power  of  the 
sun's  atmosphere. 

7.  Variations  in  the  temperature  of  space. 

8.  A  coincidence  of  an  Aphelion  winter  with  a  period 
of  maximum  eccentricity  of  the  earth's  orbit. 

-     9.     A  combination  of  8  and  2. 

10.  The  views  of  Sir  Robert  Ball,  LL.  D.,  etc.,  as 
expressed  in  his  recent  work,  The  Cause  of  an  Ice  Age* 

The  first  of  these  theories  is  universally  admitted, 
and  taught  in  even  elementary  works  on  Physical  Geog- 
raphy, but  it  fails  to  account  for  all  the  phenomena  ac- 
companying the  Ice  Age,  or  to  account  for  the  disap- 
pearance of  that  age,  and,  so  far  as  the  author  is  aware, 
has  not  been  presented  in  such  form  as  to  satisfactorily 
account  for  geological  and  present  climates  in  rigid  con- 
formity with  the  facts  and  known  laws.  Nor  has  it  been 
presented  in  such  form  as  to  account  for  that  era  of  geo- 
logical climates  known  as  the  Ice  Age;  moreover,  it  fails 
to  account  for  the  disappearance  of  that  Age. 

The  second  has  been  proved  to  be  a  local  and  corre- 
lated phenomenon,  but  cannot  be  accepted  as  a  cause, 
since  glaciation  did  not  solely -depend  in  the  same  lati- 
tudes upon  elevation  above  sea  level. 

As  to  the  third,  whilst  slight  changes  in  obliquity 
have  occurred,  and  must  continue  to  occur,  the  results 
are  too  slight  and  the  distribution  of  glacial  phenomena 
is  too  general  to  warrant  the  acceptance  of  such  change 
as  a  prime  cause. 

The  fourth  is  a  necessary  consequence  of  the  first, 
but,  like  the  first,  fails  when  the  crucial  test  of  account- 
ing for  the  disappearance  of  the  continental  Ice  Sheets 
is  applied. 

*  See  also  The  Date  of  the  Last  Glacial  Epoch.  Gen.  Drayson,  R.  A. 
Science,  Nov.  25,  1892. 


10  GEOLOGICAL    AND    SOLAR    CLIMaTES, 

The  fifth,  sixth  and  seventh  theories  are  mere  hypo- 
theses, unsupported  by  either  demonstration  or  observed 
facts. 

The  eighth  has  been  presented  to  the  scientific  world 
through  the  labors  and  researches  of  that  eminent  geol- 
ogist and  physicist,  Dr.  James  Croll,  in  his  various 
articles  in  leading  scientific  magazines,  and  lastly,  in 
his  grand  contributions  to  the  subject  under  discussion, 
"  Climate  and  Time  "  and  "Climate  and  Cosmology." 

The  ninth  has  been  maintained  by  one  of  the  great- 
est English  naturalists,  Mr.  Alfred  Russell  Wallace. 
He  combines  the  theory  of  Dr.  Croll  with  that  of  Sir 
Charles  Lyell,  and  very  ably  presents  his  views  in 
1  'Island  Life." 

The  tenth  is  a  presentation  by  Dr.  Ball,  F.  R.  S.,  etc., 
of  an  interesting  demonstration,  to  the  effect  that  63  per 
cent,  of  solar  heat  reaches  either  hemisphere  during  its 
summer  exposure,  and  the  remaining  37  per  cent,  during 
winter  exposure.  Nothing  is  added  to  the  Physical 
Theory  of  Dr.  Croll,  nor  does  the  demonstration  in  any 
way  remove  the  serious  objections  which  have  been 
urged  against  Dr.  Croll's  views. 

The  strongest  support  that  has  been  given  to  any  of 
the  above  theories  is  made  by  the  arguments  and  de- 
ductions of  Dr.  Croll  and  Mr.  Wallace;  yet  they  have 
failed  to  produce  conviction,  for,  in  a  recent  work  on 
Geology,  the  author,  after  reviewing  the  various  theories 
as  to  the  cause  of  the  Glacial  Period,  uses  this  expression: 
"This  seems  to  be  by  far  the  most  probable  yet  pre- 
sented."* 

This  opinion  is  directly  given  upon  only  one — the 
ninth;  but  its  terms  are  such  that  it  embraces  all.  If 

*  Elements  of  Geology,  Le  Conte,  2d  Edition,  page  578. 


THEIR    CAUSES    AND    VARIATIONS.  11 

% 

the  ninth  is  "by  far  the  most  probable/'  it  would  be 
difficult  to  fix  the  degree  of  probability  or  improbability 
of  the  others. 

The  only  explanation  which  can  be  accepted  is  one 
which  will  admit  of  definite  proof,  and  will  satisfy  all 
the  conditions,  and  not  require  the  distortion  of  known 
facts,  by  forcibly  fitting  them  into  arbitrary  molds.  It 
must  start  from  universally  admitted  premises,  and  in 
rigid  consonance  with  known  laws,  correctly  interpret 
the  grand  eras  of  climate  which  have  marked  the  geo- 
logical history  of  our  globe,  and  further,  it  must  point 
out  and  fully  elucidate  wherein  and  why  the  present 
climates  of  our  globe  differ  so  radically  from  those  vast 
secular  variations  recorded  by  fossil  life — aye,  more,  it 
must  be  so  general  as  to  be  of  universal  force  and  ap- 
plicable to  other  members  of  the  solar  system  constituted 
as  our  globe. 

In  the  brief  review  just  made  of  the  principal  theories 
urged  by  various  scientists  as  causes  producing  the  Ice 
Age,  it  was  remarked  of  the  first  that  it  was  universally 
admitted  as  true,  and  even  taught  in  elementary  works 
on  Physical  Geography,  but  that  it  failed  to  account  for 
all  the  facts  developed  by  the  Ice  Age.  This  first  theory 
was  a  decrease  in  the  original  heat  of  the  globe,  the 
truth  of  which  is  established  by  a  mass  of  indisputable 
geological  evidence. 

The  present  conditions  are  so  radically  different  from 
any  of  the  eras  of  climate  known  to  have  existed,  that 
the  explanation  of  this  range  of  secular  changes  becomes 
the  grandest  problem  in  terrestrial  physics,  and  has  an 
important  bearing  in  the  solution  of  existing  conditions 
upon  the  other  planets. 

It  is  universally  admitted  that  this  original  heat  has 
been  so  lost  that  it  is  no  longer  a  factor  in  the  surface 


12         GEOLOGICAL  AND  SOLAR  CLIMATES, 

temperature  of  the  earth,  and  that  solar  energy  is  now 
the  controlling  source  of  heat. 

There  can  then  be  no  mistaking  the  first  nor  the 
present  condition  of  the  earth  as  regards  its  exposure 
to  the  only  two  sources  of  heat — (1)  solar  and  stellar* 
heat,  and  (2)  resident,  internal,  or  earth  heat.  There 
can  therefore  be  no  error  as  to  the  main  features  of 
the  problem. 

There  must  have  been  two  marked  eras  of  climatic 
control — (A)  a  past  era,  during  which  both  sources  were 
active;  (B)  and  the  present  era,  in  which  the  greater 
exterior  source  only  remains,  the  local  and  lesser  source 
having  been  practically  exhausted. 

Or,  in  other  words,  we  have,  first,  a  heated  globe  having 
resident  in  its  mass  a  finite  quantity  of  heat,  undergoing 
loss  and  exposed  to  an  exterior  source  of  heat  and  light, 
which  source  may  be  either  constant  or  decreasing  in 
its  energy,  but  so  slowly  that  it  may  be  considered  sen- 
sibly constant  during  the  eras  under  consideration; 
second,  the  same  globe  deprived  of  its  heat  to  such  an 
extent  that  a  crust  of  non-conducting  material  has 
formed,  the  outer  surface  of  which  is  exposed  only  to 
solar  heat,  and  whose  climates  are  entirely  controlled 
thereby.  The  objects  in  view  being  to  explain  (1)  the 
peculiar  uniformity  of  climates  prior  to  the  exhaustion 
of  the  first  source,  and  (2)  the  occurrence  of  an  age  of 
general  glaciation  in  all  latitudes  prior  to  the  establish- 
ment of  the  sole  control  of  the  exterior  source;  (3)  the 
reasons  of  the  differences  between  heat  distribution 
during  geological  and  present  climates.  Such  explana- 
tions to  be  in  strict  conformity  with  admitted  facts  and 

*  Stellar  heat  having  the  same  function  as  solar  heat,  and  being  sensibly 
a  constant  of  unknown  amount  but  much  less  than  solar  heat,  need  not  be 
separately  considered  in  further  discussion  of  the  question. 


THEIR    CAUSES    AND    VARIATIONS.  13 

known  laws,  and  without  omitting  the  one  nor  distorting 
the  other. 

To  be  explicit  we  will  state  that  the  prime  objects  are 
to  demonstrate — 

1.  That  in  the  passage  of  the  earth  from  an  era  dur- 
ing which  its  climates  have  been  controlled  by  internal 
heat  into  an  era  during  which  its  climates  are  controlled 
by  solar  heat,  eras  of  uniform  climates  must  have  been 
passed  through  during  which  isotherms  were  independent 
of  latitude. 

2.  That  before  climates  could  have  passed  under  solar 
control  tlmt  an  age  must  occur  during  which  continental 
areas  must  be  glaciated;  and  that  this  stupendous  phe- 
nomenon .  occurring  before   solar  climatic  control ,  was 
also  independent  of  latitude. 

3.  That  the  direct  cause  of  the  Ice  Age  was  a  com- 
bination of  the  remarkable   properties,   in  relation  to 
heat  and  cold,  possessed  by  the  various  forms  of  water. 
As  vapor,  in  the  form  of  fogs  and  clouds  it  prevented  the 
loss  or  receipt  of  heat  by  radiation;  as  water,  by  reason 
of  its  high  specific  heat,  it  retained  to  the  last  moment 
the  effective  remnant  of  earth  heat;  as  ice,  it  assumed  a 
solid  form,  storing  the  maximum  amount  of  cold. 

4.  To  point  out  in  a  general  way  the  fallacies  of 
previous    attempts    to    explain    geological    and    present 
climates. 

The  problem  will  be  given  in  a  general  proposition, 
which  is  capable  of  demonstration  in  perfect  accord  with 
known  laws. 

[This  demonstration  was  first  given  by  the  Author  in 
September,  1891,  and  is  reproduced  here  slightly  modified 
and  extended  from  Vol.  VIII  of  the  Transactions  of  the 
Technical  Society  of  the  Pacific  Coast.  ] 


14  GEOLOGICAL    AND    SOLAR    CLIMATES, 

THE  GENERAL   PROPOSITION.* 

GIVEN. — A  heated  globe,  constituted  and  circumstanced 
as  the  earth,  and  whose  surface  temperatures,  by  reason  of 
internal  heat,  are  above  the  boiling  point  of  water,  to  prove 
that  before  its  surface  temperatures  can  pass  under  the  con- 
trol of  the  solar  heat  (1)  that  climatic  changes  must  be  inde- 
pendent of  latitude,  and  (2)  that  the  continental  areas'^ 
must  be  glaciated. 

It  will  be  observed  that  the  surface  temperatures  of  a 
globe  thus  situated  are  entirely  controlled  by  its  own  in- 
ternal or  earth  heat;  for  between  such  surface  and  any 
external  source,  a  dense  cloud  of  vapor  must  exist.  The 
fact  that  direct  or  radiant  heat  rays  cannot  pass  through 
dense  fogs  and  clouds  is  well  known  ;t  therefore,  a  globe 

*  The  proposition  here  stated  is  applicable  to  any  planet.  It  is  probable 
that  Mars,  Venus  and  Mercury  have  passed  through  periods  corresponding 
to  our  Ice  Age;  and  that  Jupiter,  Saturn,  Uranus  and  Neptune  have  not 
reached  theirs.  A  study  of  Jupiter  in  this  connection  is  particularly  in- 
structive. Phenomena  are  presented  which/,  are  easily  explained  by  the 
theory  under  discussion.  See  ZenographicA  Fragments,  London,  1891. 
Also  the  author's  views  in  Circulation  of  the  Atmosphere  of  Planets.  Trans. 
Technical  Society  of  the  Pacific  Coast,  Vol.  XI,  No.  4,  pp.  127-143. 

t  There  were  circumstances  protecting  certain  areas,  such  as  the  "  Un- 
glaciated  Area,"  in  the  basin  of  the  Yellowstone  River,  in  North  America. 
Here  vast  and  continuous  lava  overflows  in  Wyoming,  Idaho,  Oregon  and 
Washington,  liberated  earth  heat;  which  heat,  borne  easterly  by  the  gen- 
eral circulation  of  the  atmosphere,  caused  the  precipitation  upon  the 
"  Unglaciated  Area  "  to  be  warm  rains  instead  of  snow.  To  this  region 
the  animals  of  the  tertiary  period  retreated  as  glacial  conditions  surrounded 
them.  Here  they  were  protected,  and  perpetuated  their  species,  and  in 
these  regions  vast  quantities  of  their  remains  are  found.  Mining  and 
Scientific  Press,  Feb.  14,  1892. 

The  easterly  projection  of  the  unglaciated  area  is  opposite  the  correspond- 
ing projection  in  the  lava  overflow.  How  this  simple  explanation  has 
escaped  the  researches  of  geologists  is  not  known. 

tMaury,  Physical  Geography  of  the  Sea,  6th  Edition,  p.  212,  et  seq. 
Croll,  Climate  and  Time,  p.  60,  et  seq.  Also,  Climate  and  Cosmology, 
p.  51. 


THEIR    CAUSES    AND    VARIATIONS.  15 

thus  situated  can  neither  give  off,  nor  receive  radiant 
heat.  The  peculiar  function  of  solar  heat  during  the 
existence  of  appreciable  quantities  of  earth  heat  was  to 
warm  the  upper  regions  of  the  atmosphere  and  the  outer 
surface  of  the  clouds  exposed  to  its  power,  thus  partly 
replacing  the  heat  lost  by  radiation  into  space,  and 
causing  the  store  of  earth  heat  to  last  longer. 

By  the  conditions  of  the  problem  presented,  we  thus 
have  a  globe  having  resident  in  its  mass  a  finite  quanti- 
ty of  heat  exposed  to  loss  only  by  means  of  the  gradual 
expansion  of  water  into  vapor,  and  the  exposure  of  this 
vapor  to  loss  of  heat  by  radiation  from  its  upper  surface 
into  space.  This  vapor  would  then  condense,  and  as 
rain,  snow  or  hail,  descend  all,  or  part  of  the  way  to 
the  earth,  receive  another  increment  of  heat,  and  ascend 
as  before.  A  slow  process,  but  exhaustive  in  time. 

Thus  the  property  of  water  to  assume  three  forms, 
each  of  which  possesses  remarkable  qualities  with  re- 
gard to  heat  and  cold,  afforded  the  only  means  for  ex- 
hausting the  earth  heat.  As  vapor,  it  possesses  the 
property  of  storing  more  heat  than  any  other  known 
substance;*  as  snow  or  ice  it  possesses  the  property  of 
storing  more  cold  than  any  other  known  substance. 
The  function  of  solar  heat,  until  the  exhaustion  of 
earth  heat  by  this  process,  was  simply  conservative; 
it  merely  warmed  the  upper  layers  of  the  atmosphere, 
through  whose  dense  vapor  its  heat  lays  could  not  pass. 
Clouds  being  more  translucent  than  transcalent,  light 
rays  reached  the  planetary  surface  prior  to  heat  rays. 

The  earth  may  thus  be  regarded  as  having  been  sur- 
rounded by  a  series  of  spheroidal  isothermal  shells  of 
mean  temperatures.  The  one  next  the  surface  repre- 

*  Except  hydrogen. 


16         GEOLOGICAL  AND  SOLAR  CLIMATES, 

sented  a  mean  temperature  of  212°  -f- 1°  Far. ;  t  being 
positive,  and  proportioned  to  the  greater  pressure  of  the 
heavier  atmosphere  existing.  Above  this  isothermal 
shell  were  others  representing  mean  temperatures  of  90°, 
60°,  32°,  Zero,  etc.,  to — x°  Far.,  the  extreme  cold  of 
interplanetary  space.  Between  the  two  spheroidal 
iostherms  of  32°  and — x°  Far.,  was  one  which  had  a 
mean  temperature  of  32° — y°,  and  equally  exposed  to 
both  sources  of  heat. 

That  the  spheroidal  isotherm  of  32°  Far.  was  within 
the  sphere  of  influence  of  earth  heat,  is  proven  by  the 
formation  of  snow  or  ice  at  that  temperature,  both 
being  the  resultant  of  vapor  expanded  and  raised  by 
earth  heat  to  that  height  as  a  minimum.  Moreover, 
vapor  would  have  reached  that  height  as  a  minimum 
were  solar  and  stellar  heat  suspended  for  a  definite 
period,  and  the  earth  absolutely  exposed  to  loss  by 
radiation  with  no  partial  return  of  heat,  from  exterior 
sources. 

It  therefore  follows  that  the  isotherm  equally  heated 
by  both  exterior  and  interior  sources  was  colder  than 
32°  Far.  or  below  that  temperature  at  which  snow  and 
ice  form.  (It  is  well  known  that  solar  energy  cannot 
maintain  a  temperature  as  high  as  32°  Far.  except  in 
the  lower  regions  of  the  atmosphere.) 

The  isothermal  shells  nearest  the  earth  were  spheroidal 
in  shape,  and  by  reason  of  the  conditions  their  surfaces 
were  practically  parallel  with  that  of  the  earth;  those 
most  remote  from  the  earth,  by  reason  of  solar  influ- 
ences, protruded  at  the  equator  and  flattened  at  the  poles, 
so  as  to  be  slightly  more  oblate  than  the  earth;  they 
were  sensibly  parallel  with  the  spheroidal  isotherm  now 
marked  by  the  "  snow  line."  Hence  at  the  equator  the 
direct  action  of  the  sun  was  first  felt  and  established. 


THEIR    CAUSES    AND    VARIATIONS.  17 

As  the  earth  heat  was  a  finite  quantity  exposed  to  loss, 
it  was  in  time  exhausted.  As  this  loss  proceeded,  these 
spheroidal  isothermal  shells  of  mean  temperatures  shrunk 
in  upon  the  earth,  and  their  contact  with  its  surface 
marked  the  zones  of  corresponding  climates  prevailing 
during  the  dual  source  of  heat.  Since  these  isotherms 
were  independent  of  equatorial  or  polar  exposure  to  solar 
energy  their  contacts  with  the  planetary  surface  estab- 
lished climates  independent  of  equatorial  or  polar  posi- 
tion, or  in  other  words  of  latitude;  and  not  until  those, 
whose  distance  from  the  surface  mainly  depended  upon 
solar  energy,  shrunk  to  the  surface  could  climates  ranged 
in  latitudinal  zones  be  established.  As  the  climates  es- 
tablished by  the  contact  of  the  isotherms  inside  of  32° — 
y°  Far.  were  independent  of  direct  solar  heat,  they  varied 
from  the  climates  established  by  solar  heat  alone;  hence 
the  marked  difference  between  climates  antedating  and 
succeeding  the  Ice  Age.  The  isotherms  preceding  this 
age  were  dependent  almost  entirely  upon  elevation  above 
sea  level,  fractures  and  conductivity  of  the  earth's  crust; 
those  succeeding  it  are  dependent  upon  proximity  to  the 
equator,  elevation  above  sea  level,  and  the  distribution 
of  heat  by  ocean  currents. 

At  the  expiration  of  a  period  of  time  T.,  the  earth  lost 
sufficient  heat  to  cause  the  isothermal  shell  of  90°  Far. 
to  shrink  to  the  surface  except  at  fractures,  and  a  par- 
ticularly uniform,  moist,  and  highly  torrid  climate  was 
established,  and  types  of  life  developed,  culminating  in 
the  Carboniferous  Age. 

The  crust  cooled  sufficiently  to  permit  the  demarkation 
of  the  continental  areas,  but  the  cooling  did  not  pro- 
ceed to  that  point  which  upheaved  the  massive  mountain 
ranges,  nor  greatly  depressed  the  ocean  areas.  There- 
fore, an  -ar-ear  of  low,  flat  continents,  and  shallow  hot 
2 


18  GEOLOGICAL    AND    SOLAR    CLIMATES, 

seas  followed.  The  life  of  that  period  abundantly  shows 
this  condition  from  one  pole  to  the  other,  and  the  pre- 
vailing temperature  is  distinctly  recorded  in  the  fossil 
life  of  the  Palaeozoic  and  Mesozoic  Eras. 

Light  rays  reached  the  surface  prior  to  this  time,  as 
evidenced  by  the  development  of  visual  organs  in  animal 
life. 

The  greater  part  of  the  vapors  and  gases  existing 
previously  in  the  atmosphere  were  condensed,  and  ex- 
isted upon  the  surface;  the  vapors  as  highly  heated 
oceans,  and  the  gases  in  various  combinations  of  the 
mineral  and  life  kingdoms.  Now,  in  the  oceans  thus 
formed  and  further  enlarged,  there  was  stored  up 
a  vast  quantity  of  the  original  earth  heat,  by  reason  of 
the  high  specific  heat  of  water,  from  which  it  was  not  ex- 
hausted until  the  last  moment;  and  in  this  process  of 
exhaustion,  it  must  have  maintained  the  cloud  shield, 
shutting  out  solar  heat  until  this  the  last  remnant  of 
effective  earth  heat  was  exhausted.  Not  only  this,  the 
oceans  thus  formed  had  a  mean  temperature  of  90°  +  z° 
Far.,  z  being  a  positive  increment  due  to  the  heat  re- 
ceived from  the  bottoms  and  sides  of  the  ocean.  Not 
until  the  bottoms  of  the  oceans  were  subjected  to  a  de- 
gree of  cold  approximating  that  to  which  the  continental 
areas  were  exposed  could  the  crust  be  cooled  uniformly 
and  reach  that  degree  of  uniform  thickness  and  stability 
suitable  to  the  safety  arid  comfort  of  the  human  race.* 

*  Moreover,  in  cooling  the  subjection  of  one  pole  to  glacial  and  the 
other  to  temperate  or  sub-tropical  conditions,  as  argued  by  Dr.  Croll, 
would  have  subjected  our  planet  to  very  peculiar  "cooling  strains,"  as 
they  are  termed  by  foundrymen.  Whereas  the  slow  and  uniform  cooling, 
as  herein  described,  is  productive  of  maximum  thickness,  strength  and 
uniformity  of  crust;  and,  as  will  be  explained  later,  this  crust  was  finally 
shrunk  in  upon  the  interior  mass  by  being  subjected  to  the  maximum  degree 
of  cold  to  which  it  can  be  exposed  during  the  existence _of  the  sun  as  a 
source  of  heat. 


THEIR    CAUSES    AND    VARIATIONS.  19 

At  the  expiration  of  the  period  of  time,  T',  the 
spheroidal  isothermal  shell  having  a  mean  temperature 
of  60°  Far.,  similarly  shrunk  to  the  surface  of  the  earth, 
and  a  corresponding  uniformly  temperate  climate  was 
established. 

The  further  cooling  of  the  crust  caused  its  shrinkage, 
and  a  consequent  greater  upheaval  of  those  areas  most 
exposed  to  loss  of  heat,  the  continents.  This  further 
shrinkage  caused  the  strata  formed  during  the  previous 
eras  to  be  upheaved  and  fractured,  and  the  lines  of  de- 
markation  between  oceans  and  continents  were  thus 
more  strongly  accentuated. 

The  life  developed  in  the  interim  evidences  an  approach 
to  that  of  the  present  temperate  zones,  and  its  wide  dis- 
tribution demonstrates  the  complete  control  of  the  cli- 
mates of  the  globe  by  internal  heat.  The  isothermal  lines 
were  entirely  at  variance  with  those  established  by  solar 
heat,  therefore  the  functions  of  solar  heat  remained  con- 
servative of  those  operating  on  the  surface  during  this 
period  also. 

The  extreme  and  uniform  distribution  of  fur  or  hair- 
covered  animals  and  of  the  deciduous  and  coniferous 
trees  of  the  Ceiiozoic  era  mark  further  the  control  of  a 
source  of  heat  more  uniformly  distributed  than  solar 
heat  could  possibly  be.  For  reasons  previously  given, 
this  isotherm  also  reached  continental  areas  earlier  than 
ocean  areas.  When  the  mean  temperature  of  the  land 
was  60°  the  tepid  oceans  must  have  had  a  mean  temper- 
ature of  60°+y°  Far.,  y,  like  z,  being  positive,  and  due 
to  increments  of  earth  heat  received  from  the  bottom. 

At  the  expiration  of  this  period  T',  or  at  some  time, 
T'±  a,  the  isothermal  shell  of  32°  Far.  shrunk  so  as  to 
reach  the  more  elevated  portions  of  the  continental 
areas,  and  thus  established  a  snow  line  independent  of 


0?  THE 

'UNIVERSITY 


20  GEOLOGICAL    AND    SOLAR    CLIMATES, 

the  influences  now  establishing  and  maintaining  such 
snow  line.  The  resulting  glaciation  was  controlled  by 
the  same  general  laws  that  now  exist,  only  the  distribu- 
tion of  heat  being  independent  of  latitude,  and  mainly 
dependent  upon  altitude  above  sea  level,  glaciation  of 
present  tropical  and  temperate  latitudes  was  as  certain 
to  occur  as  in  polar  regions.  The  moment  a  snow- 
flake  reached  the  earth  which  the  waning  earth  heat 
was  unable  to  melt,  the  Ice  Age  was  inaugurated; 
and  the  conditions  were  such  as  to  favor  its  exten- 
sion until  the  exhaustion  of  the  store  of  heat  be- 
neath the  oceans  and  resident  in  them,  by  reason 
of  the  high  specific  heat  of  water.  It  will  be  noted 
here  that  whenever,  in  obedience  to  the  expansive 
force  of  this  waning  earth  heat,  a  particle  of  water  was 
vaporized  and  made  the  last  round  of  its  circulation,  it 
returned  to  the  earth  in  that  form  which  stored  the 
maximum  degree  of  cold,  or,  in  other  words,  in  that 
form  which  required  the  maximum  amount  of  solar  heat 
to  change. 

From  the  moment  that  snow  began  to  accumulate, 
every  remaining  vestige  of  earth  heat  was  available 
for  producing  those  conditions  favorable  to  glacia- 
tion, namely,  warm  seas,  dense  fogs  and  cold  con- 
tinental areas;  and  every  unit  of  solar  energy  reaching 
the  upper  regions  of  the  atmosphere  was  available  for 
maintaining  those  favorable  conditions.*  Glaciation 
under  these  conditions  would  be  cumulative  until  the 
oceans,  exhausted  of  their  heat  and  lessened  in  area, 

*  The  prime  objection  which  is  urged  against  all  previous  theories  is 
their  inadequacy.  We  here  have  a  perfectly  adequate  cause— resident 
earth  heat  to  supply  evaporation  and  shut  out  solar  energy,  which  energy 
can  only  act  the  part  of  a  conservator  of  the  glacial  conditions  until  the 
exhaustion  of  earth  heat,  when  its  power  can  be  spent  in  melting  glacial 
ice,  and  in  gradually  establishing  the  present  conditions. 


THEIR    CAUSES    AND    VARIATIONS.  21 

were  no  longer  able  to  supply  the  moisture  necessary  to 
completely  shroud  the  earth  from  direct  solar  heat. 

At  the  expiration  of  the  time  T",  the  isothermal  shell, 
having  a  mean  temperature  of  32°  Far.,  shrunk  in  upon 
the  globe,  and  the  oceans  were  exhausted  of  their  store 
of  heat  and  their  bottoms  brought  in  contact  with  water 
having  a  mean  temperature  of  31°  Far.,  a  temperature 
approximating  that  of  the  ocean  depths  at  present,  and 
of  ice  in  masses. 

The  isothermal  shell  32°  Far.  was  a  spheroid  circum- 
scribing the  earth*  In  shrinking  to  the  earth  its  inter- 
sections with  the  surface  were  controlled  by  the  eleva- 
tion of  the  surface  above  sea  level,  and  by  the  local 
escape  of  earth  heat;  elevated  equatorial  or  temperate 
areas  were  therefore  as  much  exposed  to  glaciation  as 
polar  lands.  (For  maximum  depth  of  glaciation  see  page 
32.)  By  reason  of  the  high  specific  heat  of  water,  this 
isotherm  also  reached  continental  areas  prior  to  reaching 
ocean  areas. 

The  crust  beneath  the  ocean,  having  been  protected 
from  loss  of  heat  by  the  superincumbent  water,  shrunk 
to  its  final  shape  subsequent  to  that  portion  forming  conti- 
nental areas.  The  ocean  bottoms  in  thus  shrinking  ap- 
proximately to  their  present  shape  must  have  been  frac- 
tured, as  continental  areas  had  previously  been.  In  this 
way  very  considerable  increments  of  earth  heat  were  set 
free  after  glaciation  had  commenced.  This  process,  which 
is  entirely  in  consonance  with  known  laws,  would  result 
in  increasing  the  depth  of  glaciation,  or  even  in  re- 
establishing it  after  partial  recedence. 

There  would  also  result  a  complicated  series  of  crust 
movements  as  the  continents  were  relieved  of  pressure 
by  the  melting  of  the  ice  caps,  and  the  ocean  bottoms 


22         GEOLOGICAL  AND  SOLAR  CLIMATES, 

subjected  to  increased  pressure  by  the  restoration  of 
water  to  the  oceans.* 

Thus  the  same  forces  which,  even  before  the  eras  we 
have  been  considering,  must  have  built  up  upon  the 
surface  of  the  globe  mineral  forms  of  surpassing  beauty, 
only  to  be  destroyed  and  ground  down  to  give  place 
to  vegetable  and  animal  forms  of  wonderful  develop- 
ment— these  same  forces  were  called  upon  to  well  nigh 
obliterate  every  living  individual  of  both  kingdoms. 
The  efficiency  of  their  work  is  attested  in  every  zone  of 
life  from  the  equator  to  the  poles. 

The  exhaustion  of  the  residuum  of  earth  heat  in  the 
oceans  and  beneath  them  could  only  have  been  accom- 
plished by  the  same  means  as  before,  and  this  exhaus- 
tion resulted  in  the  preservation  of  those  conditions 
most  favorable  to  glaciation.  When  by  the  chilling  of 
the  oceans  to  about  31°  Far.  and  by  the  glaciation  of 
continental  areas,  the  air  was  cleared  of  obscuring  clouds 
and  fogs,  the  wonderfully  uniform  series  of  climates  was 
at  an  end. 

With  the  dominion  of  solar  heat  there  dawned  upon 
our  planet  an  era  of  climatic  zones  whose  lines  sensibly 
follow  parallels  of  latitude;  then  also  began  seasons  of 
spring,  summer,  autumn  and  winter,  with  the  varying 
changes  of  the  earth's  annual  round. 

The  climatic  changes  during  the  control  of  earth  heat,, 

*  It  will  again  be  noted  that  the  isotherms  inside  of  32° — y°  Far.  were 
maintained  by  earth  heat,  and  therefore  independent  of  equatorial  or  polar 
exposure  to  solar  heat.  Consequently  their  intersections  were  upon  differ- 
ent lines  from  those  isotherms  exterior  to  32° — y°  Far.,  which  latter  were 
mainly  dependent  upon  solar  heat.  It  will  also  be  observed  that  solar 
heat,  when  it  reaches  the  lower,  denser  regions  of  the  atmosphere,  is 
trapped  and  therefore  capable  of  establishing  and  maintaining  higher  tem- 
peratures than  in  the  upper  atmosphere. 


THEIR    CAUSES    AND    VARIATIONS.  23 

and  within  the   range  of  geological  research  extended 
over  eras: 

1.  An  era  of  torrid  heat. 

2.  An  era  of  tropical  heat. 

3.  An  era  of  temperate  heat. 

4.  An  era  of  glacial  cold. 

Each  merged  gradually  into  the  others,  but  each  re- 
corded its  period  of  existence  in  unmistakable  terms,  all 
shrouded  from  the  direct  action  of  solar  heat,  and  all 
evidencing  by  the  life  produced,  the  stifling,  smothered 
character  of  the  climate. 

That  solar  heat  was  shut  out  from  the  surface  of  the 
earth  during  the  Ice  Age  is  geologically  recorded  in  the 
glaciation  of  the  North  Temperate  Zone  over  conti- 
nental areas,  where  solar  energy  has  removed  glacial 
cold  and  established  in  its  stead  a  mean  annual  tem- 
perature of  40°  Far.,  and  in  the  torrid  zone  it  has 
removed  glacial  cold  and  established  a  mean  annual 
temperature  of  76°  Far.,  where  snow  never  falls. 

Consequently,  in  a  heated  globe,  constituted  and  cir- 
cumstanced as  the  earth,  exposed  to  two  sources  of  heat, 
internal  heat  and  solar  heat,  before  its  climates  or  sur- 
face temperature  can  pass  under  the  control  of  solar  heat 
climatic  changes  must  be  independent  of  latitude  and 
the  continental  areas  must  be  glaciated. 

A  GENERAL  COMPARISON  OF  THE  DEMONSTRATION  WITH 
THE  FACTS  OF  GEOLOGY. 

The  dawn  of  the  Archaean.  Era  found  the  earth  a 
heated  globe^merging  from  an  unrecorded  and  unfathom- 
greater  heat.  The  crystalline  character  of  the 
earliest  rocks  demonstrates  the  high  temperature  which 
prevailed  upon  the  surface  at  that  time.  Such  being 


24  GEOLOGICAL    AND    SOLAR    CLIMATES, 

the  temperature  of  the  surface,  it  is  beyond  question 
that  the  existence  of  uncombined  water  upon  it  was  an 
impossibility,  and  as  vapor  it  could  only  shroud  the 
earth  in  dense  clouds.  The  earth  heat  was  as  effect- 
ually shut  in  from  loss  by  radiation  as  was  solar  heat 
shut  out  from  reaching  the  surface. 

As  this  finite  amount  of  earth  heat  could  only  escape 
by  doing  work  in  the  expanding  of  water  to  vapor,  vast 
eras  of  time  must  elapse  before  the  work  done  could 
exhaust  the  available  heat.  The  process  of  exhaustion 
was  further  retarded  by  two  causes:  1st,  the  heating  of 
the  outer  layers  of  the  atmosphere  by  solar  heat;  and 
2d,  the  low  conductivity  of  the  strata  of  the  earth  itself; 
consequently  the  climates  of  the  earth,  until  the  final 
exhaustion  of  earth  heat,  being  controlled  by  a  uniformly 
distributed  supply,  were  of  remarkable  uniformity.  The 
denudations,  faults  and  fractures 'of  its  crust  set  free 
additional  increments  of  heat  but  slowly,  so  that  the 
torrid,  tropical  and  temperate  eras  Were  longer  than  the 
frigid  era. 

During  the  existence  of  sensible  quantities  of  earth 
heat  the  oceans  must  have  been  heated  from  the  bottom, 
and  cooled  at  the  surface  by  evaporation.  The  evapora- 
tion from  the  total  ocean  surface  under  such  conditions 
would  give  rise  to  much  more  extensive  cloud  formations 
than  at  present.  Indeed,  the  record  of  temperatures 
and  character  of  life  are  such  as  to  warrant — nay,  even 
force — the  conclusion  that  the  whole  earth  was  one  vast 
hothouse,  from  which  solar  heat  was  shut  out,  and 
throughout  which  a  uniform  temperature  was  prevalent 
from  pole  to  pole. 

Solar  heat  does  not  penetrate  the  thinnest  cloud;  even' 
a  fog  through  which  the  form  of  the  sun  is  distinctly 


THEIR    CAUSES    AND    VARIATIONS.  25 

visible  shuts  out  nearly  all  direct  solar  heat.*  The  failure 
in  the  past  to  recognize  the  climatic  influence  which  the 
factor  earth  heat  was  able  to  produce,  and  the  endeavor 
to  ascribe  to  solar  energy  the  climatic  conditions  exist- 
ing during  the  activity  of  earth  heat,  has  caused  all  the 
mystery  and  error  of  attempts  to  explain  the  climatic 
phenomena  prior  to  and  during  the  Ice  Age. 

Once  realize  the  peculiar  influence  and  domination  of 
earth  heat,  and  these  mysteries  and  errors  fade,  and  the 
whole  system  of  preglacial  and  glacial  climates  becomes 
simple. 

The  function  of  solar  heat  during  the  activity  of  earth 
heat  could  be  none  other  than  conservative  of  the  latter; 
such  function  it  is  now  performing  for  the  great  planets, 
Jupiter  and  Saturn,  and  probably  Uranus  and  Neptune, 
whose  surfaces  are  shrouded  from  our  view  by  clouds. f 

*  The  truth  of  this  fact  is  easily  established  by  either  observation  or 
experiment.  At  the  close  of  a  hot  day  should  a  slight  cloudiness  super- 
vene, the  loss  of  heat  by  radiation  from  the  surface  is  checked;  the  air  at 
the  surface,  and  the  surface,  remain  at  the  same  temperature,  and  nature's 
delicate  differential  thermometer — the  deposition  or  non-deposition  of 
dew— records  the  non-transcalency  of  clouds,  in  terms  worthy  of  consid- 
eration. 

Again,  let  two  delicate  thermometers  be  exposed,  one  to  the  air  tempera- 
ture and  the  other  in  addition  to  direct  solar  rays;  the  latter  will  mark  the 
increased  temperature  due  to  such  exposure.  Upon  the  intervention  of  a 
cloud,  or  even  a  jet  of  steam,  both  instruments  will  mark  the  same  tem- 
perature. 

See  Physical  Geography  of  the  Sea.    Maury,  6th  ed.r  p.  212,  et  seq. 

Climate  and  Time,  Croll,  p.  60,  et  seq. 

Climate  and  Cosmology,  Croll,  p.  51. 

t  Astronomers  agree  that  there  must  exist  upon  Jupiter  a  high  degree  of 
heat,  and  yet  no  refinement  of  thermometric  determinations  can  detect 
any  more  heat  from  the  Jovian  surface  than  should  be  reflected  from  the 
sun. — See  Young's  General  Astronomy,  page  353;  also  History  of  Astronomy 
During  the  Nineteenth  Century.  Clerke,  pp.  335-338. 


26  GEOLOGICAL    AND    SOLAR    CLIMATES, 

Climatic  Facts  Established  by  Fossil  Life. 

It  would  be  impossible,  in  the  limits  to  which  it  is 
necessary  to  restrict  this  paper,  to  review  the  vast  array 
of  facts  which  could  be  brought  forward  to  demonstrate 
the  perfectly  uniform,  torrid  character  of  the  climates 
of  the  globe  during  the  Palaeozoic  Era. 

From  the  81st  degree  of  north  latitude  through  every 
range  of  present  climates  to  the  confines  of  the  south 
frigid  zone,  the  life  systems  attest  the  stifling  hothouse 
character  of  the  climate.  The  species  of  plant  life  and 
animal  life,  whether  of  land  or  marine  forms,  varied  less 
from  the  torrid  to  the  frigid  zones  than  corresponding 
species  upon  different  continents  in  the  same  zone  do  now. 
Nowhere  below  the  Permian  deposits  can  fossil  life  be 
recognized  that  does  not  belong  to  an  ultra-tropical  type. 
Such  uniformity  of  temperature  is  impossible  under  solar 
control,  and  hence  can  only  belong  to  a  climate  con- 
trolled by  earth  heat. 

In  reviewing  the  temperatures  recorded  by  the  fossil 
life  of  the  Palaeozoic  Era,  the  fact  becomes  apparent  that 
nowhere  upon  the  surface  of  the  globe  during  that  era 
were  there  any  zones  of  temperature.  The  whole  surface 
was  subjected  to  one  universal  torrid  climate — the  life 
developed  was  uniform  in  its  general  character  from  the 
Arctic  to  the  Antarctic  circle.  Under  no  possible  con- 
ditions could  such  uniformity  of  climate  have  been 
established  and  controlled  by  solar  heat  alone.  Hence 
during  this  period  earth  heat  was  the  controlling  source. 

This  era  merged  gradually  into  the  Mesozoic  era  of 
tropical  heat,  during  which  the  forms  of  life  developed 
into  higher  types,  and  their  range  of  distribution  demon- 
strates the  still  perfect  uniformity  of  climate.  One 
peculiar  and  significant  fact  is  recognizable  in  com- 


THEIR    CAUSES    AND    VARIATIONS.  27 

paring  the  land  forms  with  the  marine  forms  of  life. 
The  former  developed  types  more  suitable  to  tropical 
climates,  while  the  latter  held  more  tenaciously  to  the 
torrid  types,  thus  proving  the  more  rapid  loss  of  heat 
by  the  continents. 

The  fossil  life  of  the  Cenozoic  era  corroborates  to  a 
remarkable  degree  the  still  perfect  uniformity  of  climate. 
Throughout  Greenland,  Iceland,  Lapland  and  Spitz- 
bergen,  as  well  as  throughout  present  temperate  and  trop- 
ical zones,  a  perfectly  uniform  and  temperate  climate  ex- 
isted. The  flora  and  fauna  of  the  lower  Mississippi 
valley  flourished  in  those  localities  in  which,  during  the 
Paleozoic  era,  only  gigantic  Ferns,  Lycopods,  Calamites 
and  corresponding  plant  and  animal  life  could  be 
found,  and  where  now  only  a  stunted  Arctic  life  can 
exist. 

The  palseontological  evidence  of  the  Mesozoic  and 
Cenozoic  eras  is  equally  convincing  as  to  the  perfectly 
uniform  tropical  climate  of  the  one  and  temperate  and 
later  frigid  climates  of  the  other. 

During  the  latter  part  of  the  Tertiary  and  early  Quat- 
ernary periods  identical  types  of  life  existed  in  all  parts 
of  Europe,  Asia  and  America  and  a  uniformly  temperate 
climate  prevailed  over  the  whole  northern  hemisphere 
entirely  at  variance  with  the  extreme  range  of  tempera- 
tures now  embraced  in  that  half  of  the  globe. 

The  control  of  the  waning  earth  heat  was  simply 
dying  out,  and  had  reached  that  stage  in  which  it  was 


28  GEOLOGICAL    AND    SOLAR    CLIMATES, 

no  longer  .able  to  maintain  the  high  temperatures  of 
previous  eras.* 

The  evidence  that  the  high  specific  heat  of  water  held 
the  last  available  remnant  of  earth  heat,  and  thus  per- 
petuated its  control  of  climates,  is  beyond  dispute,  as 
presented  by  the  conditions  culminating  in  the  Ice  Age. 

Whatever  may  be  the  doubts  as  to  the  actual  date  of 
the  Ice  Age.,  there  is  no  disputing  the  fact  that  the  evi- 
dences establishing  the  culmination  of  that  Age  are 
found  above,  or  since  the  Tertiary,  and  beloiv  or  before 
the  Modern  Era.  . 

*  The  author  is  aware  that  this  statement  is  at  variance  with  the  opin- 
ion of  many  Geologists  of  high  repute,  as  may  be  seen  from  the  following 
quotations:  "It  is  evident  that  the  idea  of  connecting  the  phenomena  of 
the  internal  heat  of  the  globe  with  terrestrial  climates,  whether  of  the 
present  or  of  past  geological  ages,  must  be  entirely  abandoned,  as  it  has 
been,  by  most  writers  on  this  subject.  The  hypothesis  cannot  be  allowed 
to  stand  as  even  one  of  the  possible  theories  of  climatic  change." — The 
Climatic  Changes  of  later  Geological  Times.  Whitney,  p.  261. 

"  The  first  theory  brought  forward  to  account  for  glaciation  was  that 
the  earth,  having  been  originally  in  a  fiery  state,  had  in  cooling  passed 
from  a  condition  of  universal  warmth  to  a  more  and  more  frigid  state, 
until  the  present  conditions  were  attained.  This  is  the  least  tenable  of 
all  theories,  for  it  neglected  the  now  evident  fact  that  there  had  been 
changes  from  cold  to  warmth  and  back  again  to  cold.  However,  as  it  was 
invented  before  the  existence  of  glacial  periods  was  suspected,  it  long 
commanded  a  general  assent,  and  was  the  opinion  that  held  the  ground 
until  near  the  middle  of  this  century." — Glaciers.  Shaler  &  Davis,  p.  70. 

The  physicists  who  have  held  that  earth  heat  was  a  cause  of  the  Ice  Age 
are  Prof.  E.  Frankland,  F.  K.  S.,  Prof.  A.  Woeikof  and  SJtartorius  von 
Walterhausen.  Not  one  of  the  three,  however,  seems  to  have  had  a  clear 
conception  of  all  the  facts  and  conditions  although  their  views  were  in  the 
main  sound. 

The  author  hopes  to  extend  the  views  held  by  these  writers  and  to  show 
that  the  whole  range  of  climates  as  recorded  by  fossil  and  existing  life  is 
capable  of  correct  interpretation,  in  accordance  with  known  laws,  and 
without  the  intervention  of  suppositions  and  assumptions.  And  more- 
over, to  base  his  deductions  upon  a  general  plan  applicable  to  any  planet 
and  capable  of  explaining  conditions  prevalent  upon  other  planets,  notably 
upon  Jupiter  and  Mars. 


THEIR    CAUSES    AND    VARIATIONS.  29 

Between  these  two  periods  there  is  abundant  evidence 
from  every  climate,  from  every  zone  of  present  life,  that 
the  continents  were  glaciated. 

Europe  and  Asia,  North  and  South  America,  Africa 
and  Australia,*  all  present  glacial  strise,  boulder  deposits, 
and  other  marked  evidences  of  glaciation  at  the  same 
period,  just  antedating  the  Modern  Era,  or  during  the 
Quaternary  period. 

When  we  examine  the  evidence  found  in  one  of  the 
present  climatic  zones,  this  change  of  climate  from  an 
ultra-torrid  successively  to  a  torrid,  tropical,  temperate, 
and,  lastly  frigid  character,  is  not  only  very  marked, 
but  is  everywhere  the  same. 

*  To  those  interested  in  a  verification  of  this  very  wide  distribution  of 
glaciation,  the  following  short  list  of  authorities  is  recommended: 

Asia. — The  Great  Ice  Age  (Giekie);  Note  on  the  Glaciation  of  parts 
of  the  Valleys  of  Jhelan  and  Scind  Eivers,  in  the  Himalaya  Mount- 
ains of  Kashmere,  Lat.  34°  N.  (Capt.  A.  W.  Sleff),  F.  G.  S.;  Jour. 
Geol.  Soc,,  London,  vol.  xlvi,  p.  66;  Mem.  Geol.  Survey  of  India,  vol. 
xxii,  also  vol.  xiv;  Kecord  Geol.  Survey  of  India,  Nov.,  1880;  Jour.  Asiatic 
Society,  Bengal,  xxxvi,  p.  113;  Brit.  Association  Report,  1880;  Text  Book 
of  Geology,  A.  Giekie,  LL.  D.,  etc.,  p.  911. 

Europe. — The  European  Glacial  Literature  is  too  extensive  to  mention. 

America. — The  Ice  Age  in  North  America  (Wright);  U.  S.  Geological 
Reports;  State  Geological  Reports  of  Ohio,  Kentucky,  Pennsylvania,  New 
York,  Minnesota,  Nebraska,  Colorado,  Illinois,  etc.;  Virginia,  Am.  Jour. 
Sci.,  vol.  vi,  p.  371;  California,  Am.  Jour.  Sci.,  vol.  iii.p.  325,  vol.  x,  p.  26. 

South  America. — Geological  Sketches,  Agassiz,  p.  154,  et  seq.;  Geol.  and 
Physical  Geog.  of  Brazil  (Prof.  Ch.  Fred.  Hartt),  pp.  22,  28-9,  469-70, 
490,  558. 

Africa. — Geol.  of  South  Africa  (Stow);  Quart.  Journ.  Geol.  Soc.,  Lon- 
don, vols.  xvii  and  xviii. 

Australia  and  New  Zealand.— Climate  and  Time  (Croll),  p.  295;  Am. 
Jour.  Sci.,  vol.  32,  third  series,  p.  224;  Proc.  Linnsean  Soc.,  N.  S.  W.,  May, 
1886;  Prestwich's  Geol.,  vol.  ii,  p.  467;  Rep.  Brit.  Assn.,  1881,  p.  742. 

"The  shrunken  or  vanished  ice  of  mountain  ranges  is  indeed 
equally  characteristic  of  the  Himalaya,  the  Lebanon,  the  Alps,  the  Scan- 
dinavian chain,  the  great  chains  of  North  and  South  America,  and  of  other 
minor  ranges  and  clusters  of  mountains." — Ramsay,  Quart.  Jour.  Geol. 
Soc.,  1862,  p.  204. 


30  GEOLOGICAL    AND    SOLAR    CLIMATES, 

Upon  the  establishment  of  solar  heat  in  the  control 
of  surface  temperatures,  we  find  the  isotherms  entirely 
at  variance  with  those  ante-dating  the  Ice  Age.  We 
find  also  strong  corroboration  in  the  lines  of  retreat  of 
the  continental  ice  caps.  These  lines  are  sensibly  par- 
allel with  the  isotherms  established  by  solar  heat,  prov- 
ing that  solar  heat  was  the  cause  of  the  disappearance 
of  glacial  conditions. 

These  facts  distinctly  prove  the  totally  different  source 
and  distribution  of  heat  before  and.  since  the  Ice  Age, 
and  that  upon  the  inauguration  of  climates  controlled 
by  solar  energy,  an  obliteration  of  the  conditions  left 
upon  the  dying  out  of  earth  heat  set  in.  Along  that 
zone  most  exposed  to  solar  energy  conditions  and  life 
corresponding  to  the  tropical  conditions  of  Cenozoic 
times  have  been  established;  along  those  zones  mod- 
erately exposed  to  solar  energy  the  newly  established 
conditions  are  analogous  to  the  universally  temperate 
climate  of  the  latter  Tertiary  and  early  Quaternary 
periods;  whilst  in  those  zones  least  exposed  to  solar  en- 
ergy a  removal  of  glacial  conditions  is  yet  in  progress.* 

Wherever  fossil  life  has  been  developed  the  order  of 
climates,  as  thus  recorded  has  been:  First,  torrid; 
second,  tropical;  third,  temperate;  fourth,  frigid;  and 
fifth,  the  life  appropriate  to  the  zone  of  solar  climate — 
irrespective  of  that  existing  previous  to  the  Ice  Age. 
The  same  order  is  true  for  any  portion  of  either  tem- 
perate zone;  under  the  equator  the  order  of  climates 

*  Many  geologists  are  misled  by  the  greater  modification  of  tropical 
drift  by  sub-aerial  agencies.  Having  been  longer  exposed  to  such  agencies, 
greater  modifications  are  to  be  expected.  The  apparent  improbability  of 
tropical  glaciation  seems  to  deter  many  scientists  from  believing  that  such 
glaciation  could  ever  have  occurred,  yet  the  same  scientists  will  accept  the 
fact  that  fossil  life  establishes  the  existence  of  tropical  or  even  torrid  con- 
ditions within  the  polar  circles  during  past  ages. 


THEIR    CAUSES    AND    VARIATIONS.  31 

has  been  the  same,  except  a  return  to  tropical  conditions 
and  life.* 

In  the  North  frigid  zone  this  same  order  of  climates 
has  been  found,  except  that  there  has  been  no  change 
from  the  conditions  left  upon  the  dying  out  of  earth 
heat;  in  other  words,  solar  energy  has  not  removed 
glacial  cold  in  those  regions  least  exposed  to  its  action. 

The  removal  of  glacial  conditions  has  been  less  in  the 
Antartic  than  in  the  Arctic  regions,  partly  from  causes 
pointed  out  by  Maury,  and  more  fully  treated  by  Dr. 
Croll.  This  removal  has  also  been  subjected  to  varia- 
tions due  to  the  mild  astronomical  influences  ascribed 
by  Adhemar,  Croll,  Ball,  Drayson  and  others,  as  suffi- 
cient to  produce  glaciation. 

These  astronomical  causes  undoubtedly  must  have  pro- 
duced slight  secular  variations  in  the  relative  exposures 
of  the  two  hemispheres  to  solar  heat — but  they  have  not 
been  demonstrated  to  be  of  sufficient  influence  to  produce 
glaciation,  and. in  no  way  could  they  sensibly  affect 
climates  prior  to  the  establishment  of  the  control  of 
solar  heat.  (See  page  41.) 

The  distribution  of  heat,  prior  to  the  Ice  Age,  as 
recorded  by  fossil  life,  being  entirely  at  variance  with 
that  now  found,  and  being  entirely  independent  of 
proximity  to,  or  distance  from,  the  equator,  distinctly 
proves  that  climates  were  established  and  maintained 
independently  of  solar  heat,  and  hence  belong  to  the  only 
other  source,  viz.,  earth  heat. 

It  is  also  evident  that  under  no  possible  conditions 
could  solar  energy  maintain  a  torrid,  tropical,  temperate 
and  lastly  glacial  climate  over  the  whole  range  of  the 
present  zones  of  climates,  and  that  this  uniform  distri- 

*See  Geological  Sketches,  Agassiz,  p.  154,  etseq.  Also  Physical  Geography 
and  Geology  of  Brazil,  Prof.  Ch.  Fred.  Hartt,  pp.  22,  28,  29,  217,  469,  470. 


32  GEOLOGICAL    AND    SOLAR    CLIMATES, 

bution  of  heat  prior  to  and  during  the  glaciation  of  the 
globe  was  due  to  an  evenly  distributed  supply  from  a 
constantly  and  uniformly  decreasing  source. 

Moreover,  the  wide  distribution  of  glaciation  over  the 
present  temperate  and  torrid  zones  is  a  distinct  proof  of 
the  exclusion  of  solar  heat  from  these  regions  during 
glaciation.  Under  no  possible  circumstances  could  tem- 
perate North  America,  Europe  and  Asia  and  tropical 
South  America  have  been  glaciated  unless  these  regions 
were  shut  out  during  glaciation  from  that  solar  energy, 
which  when  admitted  has  removed  glacial  conditions. 

Glacial  dispersion  followed  one  of  two  general  laws: 
First,  the  great  centers  or  belts  from  which  dispersion 
took  place  in  apparent  disregard  of  the  slope  of  the 
ground  were  areas  most  exposed  to  cyclonic  activity  and 
resulting  precipitation.  Second,  minor  centers  of  dis- 
persion (or  local  glacial  dispersion)  were  elevated  lands, 
subjected  to  uniform  precipitation'.* 

Since  glacial  conditions  in  the  northern  hemisphere 
were  removed  from  southerly  towards  northerly  latitudes, 
the  gradients  were  increased  southerly  and  decreased 
northerly  from  lines  of  maximum  glaciation.  Glacial 
transportation  was  likewise  modified.  The  reverse  of 
these  directions  prevailed  in  the  southern  hemisphere. 

Glaciated  areas  have  been  partly  relieved  of  their  loads 
of  ice  at  rates  and  times  proportional  to  solar  exposure, 
and  upon  lines  parallel  with  present  mean  annual  iso- 
therms. Wherever  remnants  of  the  continental  ice  sheets 
of  the  Ice  Age  yet  rest,  this  retreat  is  still  in  progress 
from  the  same  cause. 

The  ascription  of  great  elevations  above  sea  level  dur- 

*  See  the  author's  views  in  Physical  and  Geological  Traces  of  Permanent 
Cyclone  Belts.  Trans.  Technical  Society  of  the  Pacific  Coast,  Vol.  VIII, 
No.  1,  June,  1891. 


THEIR    CAUSES    AND    VARIATIONS.  33 

ing  the  Ice  Age  is  natural,  and  such  apparent  greater 
elevation  is  due  to  tivo  causes  during  this  period,  whilst 
due  to  only  one  cause  during  previous  eras.  As  the 
surface  of  the  earth  became  subjected  to  a  temperature 
of  31°  Far.  under  the  oceans,  and  a  corresponding 
temperature  under  the  continental  ice  caps,  contraction 
and  consequent  elevation  were  continued  as  before;  and 
as  snow  was  piled  up  upon  the  continents,  water  was 
withdrawn  from  the  oceans;  for  each  million  square 
miles  of  continental  ice  cap  three  hundred  feet  thick  a 
corresponding  three  million  square  miles  of  ocean  was 
lowered  one  hundreed  feet.  The  continental  ice  caps 
already  approximately  known  were  too  vast  not  to  have 
lowered  the  sea  level  to  a  marked  degree. 

The  apparent  general  depression  after  the  Ice  Age  is 
as  natural.  By  the  melting  of  the  greater  portion  of 
the  ice  caps,  and  the  evaporation  of  vast  inland  seas, 
the  sea  was  approximately  restored  to  the  level  existing 
prior  to  the  Ice  Age,  thus  causing  an  apparent  sinking 
of  the  land. 

The  great  difference  between  climatic  conditions  prior 
to  and  since  the  Ice  Age  is  very  marked  around  inland 
seas  and  basins  without  drainage.  Lake  Bonneville  and 
Lake  Lahontan,  in  the  United  States,  and  the  greater  area 
once  occupied  by  the  Caspian  and  other  seas,  evidence 
the  superior  dampness  and  rainfall  antedating  the  Ice 
Age.  During  the  control  of  earth  heat  the  oceans  were 
heated  to  their  bottoms,  and  furnished  moisture  enough 
to  keep  these  great  depressions  full  of  water  and  to  sup- 
port a  dense  life  upon  now  desert  areas.  The  dry  air  of 
the  modern  era  has  not  only  absorbed  the  water  in  these 
vast  lakes,  and  restored  it  to  the  oceans,  but  vaster  areas 
have  been  converted  into  deserts  by  the  unequal  distri- 
bution of  heat  and  moisture  under  solar  control. 
3 


34  GEOLOGICAL  AND  SOLAR  CLIMATES, 

PALEOZOIC  GLACIATION. 
"  Glacial  Periods." 

It  is  probable  and  may  be  regarded  as  a  fact  that  upon 
certain  of  the  oldest  and  highest  mountains,  glaciation 
was  inaugurated  during  the  Paleozoic  Era,  to  slowly  dis- 
appear by  the  gradual  setting  free  of  earth  heat  by  vast 
fractures  of  the  crust  or  to  remain  as  local  glaciation  until 
the  Ice  Age.  Isolated  glacial  deposits  of  this  nature  which 
were  independent  of  solar  exposure  readily  account  for 
the  early  "Glacial  Periods,"  which  were  evidently  local 
phenomena  antedating  the  Ice  Age.  It  is  neither  logi- 
cal nor  reasonable  to  interpret  the  finding  of  evidences 
of  early  local  glaciation  into  a  Glacial  Period,  for  local 
glaciations  are  found  now  in  the  Alps  and  upon  certain 
peaks  of  the  Sierra  Nevada,  and  even  in  the  torrid  zone, 
but  they  by  no  means  establish  the  present  existence  of 
a  Glacial  Period. 

Evidences  of  glaciations  antedating  the  Ice  Age  are 
wholly  of  a  mechanical  nature — namely,  the  transport- 
ation of  boulders,  striae,  etc.  No  corroborative  evidence 
of  fossil  life  of  Arctic  habits  has  been  found.  This  is 
particularly  the  case  of  marine  fauna  and  flora,  which 
may  be  held  as  the  only  indisputable  evidence  of  an  Ice 
Age. 

Granting  that  the  evidences  found  be  sufficient  to  estab- 
lish Palaeozoic  glaciations,  the  absence  of  fossils  of  an 
Arctic  type  proves  such  glaciations  to  have  been  local 
and  possibly  of  short  duration,  for  had  such  glaciation 
been  general  and  of  long  duration  both  plant  and 
animal  life  would  have  been  modified  into  temperate 
and  Arctic  types,  as  occurred  later  when  general  glacia- 
tion ensued. 

It  is  apparent  that  the  isotherm  32°  Far.  could  have 
shrunk  for  a  short  period  to  the  tops  of  mountains 


THEIR    CAUSES    AND    VARIATIONS.  35 

and  that  glaciers  could  have  formed  and  coursed  their 
way  into  a  subtropical  growth  below;  and  that  these 
conditions  would  be  removed  by  the  setting  free  of 
earth  heat  with  the  consequent  rise  in  temperatures. 

These  changes  followed  too  closely  or  were  too  limited 
in  area  to  permit  the  evolution  of  forms  of  continental 
life  adapted  to  temperate  and  Arctic  conditions. 

Palaeozoic  glaciations  in  110  way  conflict  with  the 
demonstration  herein  given — they  are  really  corobora- 
tive  of  the  other  facts  advanced  to  prove  that  prior  to 
the  Ice  Age  solar  heat  was  shut  out  from  the  surface. 
For  the  evidences  of  Palaeozoic  glaciation  occur  in  tem- 
perate and  tropical  latitudes  adjacent  to  fossil  life  indi- 
cative of  high  temperatures.  Early  glaciations  were 
dependent  only  upon  elevation,  and  latitude  did  not  in- 
fluence their  occurrence  in  any  way  whatever,  and 
whether  in  Norway  or  India  these  glacial  conditions  were 
coexistent  with  tropical  life  at  a  lower  elevation  and 
equally  independent  of  latitude. 

When  the  crust  became  too  thick  and  non-conducting 
to  yield  a  sufficient  supply  of  heat  to  hold  mean  tem- 
peratures at  a  higher  degree  of  heat  than  32°  Far.  this 
isotherm  shrunk  to  the  surface  only  to  be  removed 
by  solar  heat.  Since  the  position  of  this  isotherm  was 
independent  of  latitude  its  intersections  with  the  surface 
depended  only  upon  elevation,  and  as  the  continents  lost 
their  heat  more  rapidly  than  oceans,  the  latter  were  the 
last  to  fall  to  32°  Far. 

As  in  previous  eras  torrid,  tropical  and  temperate  life 
had  existed  in  Spitzbergen,  France  and  Brazil  independ- 
ent of  the  latitudes  of  these  countries,  so  too  were  glacial 
conditions  equally  independent  of  latitudes.  But  in  the 
removal  of  glacial  conditions  the  isotherms  of  solar  cli- 
mates were  necessarily  followed. 


36 


Thus  the  Ice  Age  marks  the  date  at  which  the  climates 
of  the  globe  passed  from  the  control  of  earth  heat  to 
that  of  solar  heat.  The  great  specific  heat  of  water  re- 
tained in  the  oceans,  the  energy  necessary  to  maintain 
the  cloud  shield  shutting  out  solar  heat  until  both  land 
and  ocean  areas  could  be  equally  cooled  and  contracted, 
thus  ensuring  the  maximum  degree  of  thickness  and 
stability  to  the  crust.  The  mysteries  of  geological 
climates,  interpreted  by  known  laws,  applicable  alike  to 
all  members  of  the  solar  system,  develop  thus  into  a 
system  beautiful  in  its  simplicity. 

Once  realize  that  the  surface  temperatures  of  the  globe 
were  at  one  era  in  the  past  too  high,  by  reason  of  inter- 
nal heat,  to  permit  water  to  remain  upon  the  surface, 
and  the  peculiar  properties  possessed  by  the  various 
forms  of  water  and  their  relations  to  heat  and  cold,  and 
follow  out  these  facts  to  their  natural  and  logical  con- 
clusion, and  the  whole  mystery  of  geological  climates 
clears  up  and  becomes  simple. 

MATHEMATICAL  CALCULATIONS  AS  TO  THE  DURATION  OF 
EARTH  HEAT. 

It  would  not  be  proper  to  make  the  foregoing  inter- 
pretation of  the  cause  of  geological  climates  without 
briefly  referring  to  the  various  mathematical  calculations 
which  have  been  made  by  high  authorities,  and  which 
reach  conclusions  materially  differing  from  the  deduc- 
tions herein  presented. 

The  arguments  of  Sir  Wm.  Thomson*  and  others,  to 
the  effect  that  internal  or  earth  heat  could  not  have 
affected  the  climates  of  the  globe,  by  reason  of  the  non- 

*  Phil.  Mag.  (4),  Vol.  XXV,  pp.  1-14.  Trans.  Koyal  Soc.  Edin.,  Vol.  XXIII. 
Influence  of  the  Earth's  Secular  Heat  upon  Climates.  Hopkins,  Jour. 
Geol.  Soc.,  Vol.  VIII. 


THEIR    CAUSES    AND    VARIATIONS.  37 

conductivity  of  a  comparatively  slight  thickness  of  crust, 
are  not  conclusive.     These  arguments  are  based  upon: 

1 .  An  erroneous  assumption  of  the  manner  in  which 
heat  is   lost  by  a   planet,  upon   which  there    exists    an 
atmosphere  and  a   fluid  possessing  the  physical  prop- 
erties of  water. 

2.  No  account  is  taken  in  these  calculations  of  the 
heat  set  free  by  denudations,  etc. 

3.  The  conservative  action  of  active  exterior  sources 
is  not  considered. 

1.  To  assume  that  in  a  molten  or  nearly  molten 
planet  heat  was  lost  by  direct  radiation  from  the  heated 
surface,  is  to  assume  a  mode  of  loss  that  could  not 
possibly  occur  with  the  constitution  of  our  planet, 
nor  with  one  possessing  a  constitution  generally  similar. 

At  the  period  assumed  as  the  starting  point  of  these 
calculations  the  earth's  crust  was  just  forming  from  the 
molten  state.  At  this  period,  which  has  undoubtedly 
existed,  all  uncornbined  water  must  have  been  evapor- 
ated, and  must  have  existed  as  an  enshrouding  cloud, 
shutting  out  solar  heat  and  shutting  in  earth  heat.  Our 
planet  at  this  period  must  have  presented  an  appearance 
similar  to  that  now  presented  by  Jupiter,  whose  avail- 
able internal  heat  has  evidently  not  yet  been  exhausted, 
and  upon  whose  surface  evaporation  must  be  kept  up  by 
internal  heat. 

The  loss  of  internal  heat  by  a  globe  constituted  as  our 
planet,  must  proceed,  not  by  the  radiation  and  loss  of 
heat  directly  into  space,  but  by  the  performance  of 
work  in  the  expansion  of  water  to  vapor,  the  exposure 
of  the  upper  or  cold  surface  of  the  partly  condensed 
vapor  to  loss  of  heat  by  radiation  into  space. 

The  existence  of  a  non-transcalent  cloud  shield  is 
geologically  recorded  in  most  unmistakable  terms,  as 


38  GEOLOGICAL    AND    SOLAR    CLIMATES, 

previously  explained,  by  the  maintenance  of  eras  of 
tropical,  temperate  and  frigid  climates  from  pole  to  pole — 
irrespective  of  latitude;  by  the  glaciation  of  areas  over 
which  solar  energy,  when  not  thus  shut  out,  was  capable 
of  removing  glacial  conditions  and  establishing  much 
warmer  climates;  also  by  the  contrast  of  geological 
climates  with  solar  climates,  one  independent  of,  and 
the  other  mainly  dependent  upon,  latitude. 

Thus  the  loss  of  heat  by  the  crust  must  have  pro- 
ceeded with  great  slowness;  and  the  crust  in  thus  cool- 
ing was,  by  the  laws  of  cooling  solids,  made  as  thick  as 
possible. 

2.  The  non-conductivity  of  this  cooling  crust  was  a 
cause  of  the  long,  instead  of  a  cause  of  short  duration  of 
the  internal  heat,  for  when  too  thick  to  yield  up  its  heat 
by  conductivity,  additional  increments  were  but  slowly 
set  free  by  denudations,  faults  and  fractures.    The  volume 
of  heat  thus  set  free  may  be  partly  grasped   when   it  is 
considered  that  no  portion  of  the  crust  can  be  reached 
that  is  not  built  up  of  denuded  materials.     Heat  im- 
prisoned by  a  non-conducting   crust   is  more  certain  of 
liberation  by   denudation  than  if  the  crust  were  com- 
posed of  strata  having  the  conductivity  of  beaten  silver. 

The  assumption  that  the  low  conductivity  of  the  crust 
was  a  cause  of  the  short  duration  of  earth  heat  as  a  con- 
trolling factor  is  exactly  contrary  to  the  actual  tendency 
of  such  low  conductivity. 

3.  From  the  cold  outer  surface  of  the  cloud  envelop 
heat    would  radiate   much   more   slowly  than  from  the 
more    highly    heated    surface    beneath.     Indeed,    there 
is  every  reason  to  assume  that   this  upper  surface  may 
have    been    partly  composed    of    fine    crystals    of    ice, 
as    cirrus    clouds    may    now    be.       Upon     this    upper 
surface,  whatever  may    have   been    its    condition,  was 


THEIR    CAUSES    AND    VARIATIONS.  39 

received  every  thermal  unit  of  heat  reaching  our  globe 
from  exterior  sources  from  its  development  to  the  cul- 
mination of  the  Ice  Age.  What  calculation  has  con- 
sidered this  single  factor?  which,  for  aught  we  know, 
may  have  been  but  little  less  than  the  original  available 
store.  To  what  consideration  is  any  discussion  which 
omits  this  factor  entitled? 

Having  properly  assumed  a  temperature  which  would 
necessitate  the  evaporation  of  all  uncombined  water  and 
its  suspension  above  the  heated  surface,  a  scientist 
should  follow  the  results  to  their  legitimate  and  logical 
conclusion,  and  not  neglect  the  existence  of  a  con- 
dition necessarily  coexistent  with  those  assumed. 

The  removal  of  the  enshrouding  clouds  need  not  be 
assumed;  such  removal  was  blazed  upon  the  globe  in 
broad  zones  of  climate  and  life  which  only  solar  energy 
could  maintain.  These  lines  are  as  distinctly  different 
from  those  written  by  earth  heat  as  daylight  is  from 
darkness. 

When  this  removal  did  take  place  the  fact  was  graven 
upon  our  planet  by  the  melting  of  the  massive  glaciers 
deposited  during  and  before  such  removal,  and  by  the 
establishment  of  the  existing  conditions. 

All  calculations  and  discussions  omitting  these  three 
factors  must  reach  illogical  and  erroneous  conclusions. 
The  omission  of  a  single  one  would  be  fatal,  and  entitle 
the  result  to  no  farther  consideration,  and  justifies  the 
cynical  view  that  "  There  is  something  fascinating  about 
science.  One  gets  such  wholesale  returns  of  conjecture 
out  of  such  trifling  investment  in  facts." 


40  GEOLOGICAL  AND  SOLAR  CLIMATES, 

ASTRONOMICAL  CAUSES  AND  THEIR  INFLUENCE. 

We  will  now  consider  the  effect  of  astronomical  causes. 
Dr.  Croll  has  elaborately  discussed  the  variations  in  solar 
exposure  to  which  the  two  hemispheres  of  our  planet 
have  been  and  are  subjected.* 

The  distinguished  Astronomer  Koyal  of  the  Dublin 
Observatory,  Dr.  Ball,  has  shown  that  63%  of  the  gross 
solar  energy  received  by  either  hemisphere  reaches  it 
during  summer  and  the  remaining  37%  during  winter.f 
High  authorities,  both  before  and  since  these  publica- 
tions, have  discussed  various  phases  of  these  influences, 
as  well  as  offered  remarkable  and  un verifiable  hypotheses 
regarding  the  temperature  of  space,  solar  energy,  and 
the  heat  absorptive  power  of  a  solar  envelope.  J  It  is 
not  necessary  to  attempt  a  discussion  or  elaboration  of 
these  views.  Should  the  interpretation  herein  rendered 
be  correct,  it  follows  that  variations  in  the  distance  from 
or  degree  of  solar  energy  could  not  have  directly  affected 
the  surface  temperatures  of  the  globe  prior  to  the  cul- 
mination of  the  Ice  Age,  and  that  only  since  that  age 
could  these  slight  variations  have  acted,  except  in  a 
conservative  way.  It  is  unquestionable  that  for  many 
years  past  the  temperature  of  the  northern  hemisphere 
has  risen  more  rapidly  than  the  southern.  This  condi- 
tion is  proved  not  only  by  correct  deductions  from  actual 
conditions  and  laws,  but  by  observation.  This  is  also 
recorded  geologically  by  the  greater  removal  of  glacial 
conditions  in  the  northern  hemisphere — although  in 
both  this  removal  is  yet  in  progress. 

In  a  globe  wrapped  in  a  mass  of  vapor  by  reason  of 

*  Climate  aud  Time,  Climate  and  Cosmology, 
t  The  Cause  of  an  Ice  Age,  chapters  5  and  6. 
I  Nature,  May  1891;  S.  E.  Bishop. 


THEIR    CAUSES    AND    VARIATIONS.  41 

evaporation  maintained  at  the  surface  by  its  own  heat 
and  condensed  upon  the  outer  surface  of  the  spheroidal 
cloud  envelope,  it  is  immaterial  so  far  as  surface  tem- 
peratures are  concerned,  to  what  degree  of  outside  heat 
it  may  be  subjected.  The  only  possible  effects  of  varia- 
tions in  the  distance  from,  or  intensity  of  the  exterior 
heat  source  being  to  influence  the  duration  of  the  interior 
supply  and  the  distance  therefrom  at  which  cloud  con- 
densation takes  place. 

In  a  globe  thus  enshrouded  the  same  order  of  surface 
temperatures  would  follow,  whether  revolving  in  the  orbit 
of  Venus  or  that  of  Neptune — the  actual  influences  being 
the  greater  rate  of  loss  in  the  remoter  position,  the  more 
rapid  succession  of  .geological  climates,  and  the  greater 

Mrrwmr-aJi  n  %£t*-'^&£  &r>£&L*3wy±**^cL-&^7:%Jt'  CT 

tune  necessary  for  the,  establishment  of  solar  climatic 
control.  Could  the  earth  have  been  removed  during  the 
Archaean  Age  to  the  orbit  of  Jupiter  without  disturbing 
other  conditions,  no  change  could  have  occurred  in  the 
order  of  succeeding  geological  climates  prior  to  the  Ice 
Age.  The  rate  of  receipt  of  solar  energy  would  have  been 
in  the  ratio  of  (5.2)2:1;  and  the  actual  retardation  of  loss 
would  have  been  in  this  ratio,  as  also  the  rate  of  estab- 
lishment of  solar  climatic  control;  the  crust  would  have 
cooled  quicker,  and  therefore  have  been  thinner  and  less 
stable  than  at  present. 

The  observed  movements  in  the  cloud  envelope  of 
Jupiter  present  phenomena  warranting  the  belief  that 
his  atmosphere  is  non-transcalent.*  In  this  particular 
it  resembles  the  clouded  atmosphere  of  the  earth;  and 
indicates  a  condition  analogous  to  that  of  the  earth  in 
pre-glacial  ages.  The  smaller  planets  by  reason  of  their 
lesser  masses  have  lost  their  available  resident  heat. 

*  Circulation  of  the  Atmosphere  of  Planets.— Trans.  Technical  Soc.  of 
the  Pac.  Coast,  Vol.  IX,  No.  5;  pp.  136-143. 


42  GEOLOGICAL    AND    SOLAR    CLIMATES, 

Their  atmospheres  have  become  cleared  and  are  both 
translucent  and  transcalent.  Their  surfaces  can  be 
observed,  and  their  volumes  and  densities  calculated 
with  a  reasonable  degree  of  exactness.  In  the  cases  of 
the  larger  planets  observations  are  confined  to  the  surface 
of  their  spheroidal  cloud  envelopes,  and  hence  to  these 
planets  are  ascribed  volumes  and  densities  varying 
abnormally  from  those  whose  actual  volumes  can  be 
measured.  The  satellites  of  Jupiter  possess  much  greater 
densities  than  that  ascribed  to  the  great  planet — were  it 
possible  to  measure  the  actual  volume  of  his  enshrouded 
mass  this  apparent  anomaly  would  be  in  whole  or  in  part 
removed. 

Not  knowing  the  surface  temperatures,  the  exact  com- 
position of  the  atmospheres,  nor  the  dimensions  of  the 
planetary  masses,  the  distances  to  which  the  cloud 
envelopes  of  Jupiter,  Saturn,  Uranus  and  Neptune  may 
be  expanded,  are  yet  matters  of  conjecture.  Whatever 
is  known  of  these  planets  corroborates  the  interpretation 
herein  rendered  of  the  record  of  the  geological  climates 
of  the  earth.* 

THE  ESTABLISHMENT  OF  SOLAR  CLIMATES. 

At  the  culmination  of  the  Ice  Age  the  snow  line  was 
much  lower  than  at  present,  and  elevated  landsf  at  all 
latitudes  were  deeply  glaciated;  the  seas  were  intensely 
cold.  It  is  evident  that  since  the  culmination  of  the  Ice 
Age  and  in  the  establishment  of  the  present  climates 
there  has  been  a  great  rise  in  temperatures  in  the  tropi- 

*  For  a  further  discussion  of  the  conditions  prevalent  upon  Jupiter  see 
Circulation  of  the  Atmosphere  of  Planets,  previously  quoted. 

t  Except  hot  or  warm  lava  covered  areas,  and  the  protected  or  "  uii- 
glaciated  areas  "  to  the  eastward  of  such  lava  overflows.  (See  page  44 
and  note  (t)  page  14.) 


THEIR    CAUSES    AND    VARIATIONS.  43 

cal,  temperate  and  sub-frigid  zones.  There  is  also  in- 
disputable evidence  that  this  rise  in  temperature  is  yet 
in  progress.  This  accession  of  heat  must  therefore  be 
accounted  for  by  the  correct  application  of  laws  and 
forces  now  acting,  and  it  is  not  necessary  to  go  outside 
of  these  known  laws  and  forces  to  render  a  correct  in- 
terpretation of  the  establishment  and  maintenance  of 
the  zones  of  climate  now  existing. 

It  will  be  observed  that  when  the  oceans  were  ex- 
hausted of  their  heat  and  the  lands  deeply  glaciated,  the 
crust  was  shrunk  in  upon  the  interior  mass  by  being 
uniformly  chilled  down  to  the  lowest  temperature  to 
which  a  planet,  upon  which  water  and  an  atmosphere 
exist,  can  be  subjected.  The  atmosphere  was  then 
cleared  of  clouds  and  heat  rays  from  exterior  sources 
permitted  to  reach  the  planetary  surface.  At  once 
these  rays  began  to  be  changed  into  dark  heat  rays, 
particularly  those  from  water,  and  the  trapping  of 
heat  ensued;  from  this  date  a  general  rise  in  tempera- 
tures must  follow  from  the  accession  of  heat  from  ex- 
terior sources,  until  checked  within  the  moderate  limits 
hereafter  outlined. 

The  trapping  process  thus  inaugurated  is  independent 
of  the  actual  amount  of  heat  received  whether  from  solar 
or  stellar  sources. 

Were  it  possible  for  the  now  pent-up  internal  heat  to 
raise  the  temperature  of  the  oceans,  the  crust  at  the 
bottom  of  the  oceans,  and  under  the  polar  ice  caps  to 
a  mean  temperature  of  say  68  degrees  Far.,  the  accession 
of  heat  from  exterior  sources  would  be  shut  off,  as  in 
early  Quaternary  times,  by  dense  clouds;  the  exterior 
would  be  again  shrunk  by  glacial  conditions,  the  air 
cleared  as  before  and  heat  from  exterior  sources  in  what- 
ever amounts  it  then  reached  the  surface  would  be 
trapped  as  succeeded  the  Ice  Age. 


44         GEOLOGICAL  AND  SOLAR  CLIMATES, 

This  action  must  in  turn  take  place  upon  any  planet 
upon  which  water  and  an  atmosphere  resembling  ours 
exist.  The  rate  at  which  a  planet  acquires  heat  from 
exterior  sources  is  dependent  upon  the  power  of  its  at- 
mosphere to  trap  heat;  very  slight  variations  in  the  at- 
mospheric constituents  producing  great  variations  in 
heat  trapping  power. 

Orbital  distance  being  only  a  function  of  the  amount 
received  and  not  of  the  trapping  process,  this  rise  in 
temperature  is  as  certain  to  follow  in  one  position  as 
another. 

By  thus  being  subjected  to  the  maximum  shrinking- 
strains  the  weakest  portions  of  the  crust  were  ruptured. 
The  lava  ejected  from  these  ruptures  was  spread  out 
over  the  weak  areas  in  successive  layers  of  a  few  dozen 
feet  in  thickness  until  the  added  strength  reached  that 
belonging  to  thousands  of  feet  of  solid  rock.* 

To  digress  a  moment — 

These  lava  overflows  evidently  performed  another  im- 
portant function.  The  heat  set  free  by  each  successive 
layer  could  not  have  been  lost  by  radiation  into  space, 
for  the  enshrouding  clouds  had  not  yet  been  removed. 
The  air  and  clouds  caught  this  heat  and  bearing  it  east- 
wardly  in  their  general  course  caused  warm  rains  instead 
of  snow  to  be  precipitated  upon  the  adjacent  region.  In 
this  way  the  "  unglaciated  area  "  escaped  glaciation;  in 

*  The  Columbian  Lava  Plains  of  North  America  aggregate  some  150,000 
square  miles;  the  Deccan  Lava  Plains  of  India  cover  an  almost  unbroken 
plain  200,000  square  miles  in  area.  No  Geologists  ascribe  these  lava  over- 
flows to  an  earlier  date  than  the  Tertiary;  the  author  could  find  no  reason 
to  assign  the  Columbian  Lava  Plain  to  so  early  a  period,  and  strong 
reasons  to  assign  the  continuance  of  the  flow  to  the  later  Quaternary; 
of  the  Deccan  Plain  he  is  unable  to  speak.  (See  Trans.  Geological  Society 
of  Australasia,  vol.  i,  part  vi,  p.  162,  note.  Also  Mining  and  Scientific 
Press,  Feb.  6th,  1892. 


THEIR    CAUSES    AND    VARIATIONS.  45 

this  area  are  the  "bad  lands"  of  Dakota,  whose  topo- 
graphy distinctly  shows  that  sub-aerial  denudation,  and 
not  glacial  ice  formed  the  controlling  features.  In  this 
area  are  the  great  deposits  of  tertiary  fossil  life,  in  per- 
fect form — uiicrushed  by  the  mighty  tread  of  the  glaciers 
which  surrounded  them  on  all  sides,  except  to  the  west. 
From  areas  such  as  these  went  forth  the  life  that  sur- 
vived the  glacial  winter. 

That  the  isotherm  marked  by  glacial  ice  is  yet  slowly 
retreating  upward  is  recorded  not  only  by  tradition 
and  history  but  geologically  and  physically,  as  observed 
by  every  scientist  who  has  studied  existing  glaciers.* 

This  retreat  is  a  positive  proof  of  either  a  decrease  in 
precipitation  on  the  tributary  areas,  a  rise  in  tempera- 
ture, or  both  of  these  agencies  acting  conjointly.  There 
is  no  evidence  to  show  that  a  decrease  in  precipitationf 
is  synchronously  taking  place  over  the  sub-frigid,  tem- 
perate and  tropical  regions  of  both  hemispheres,  as  is 
the  retreat  of  glaciers;  and  there  are  positive  and  active 
causes  in  force  which  have  affected,  and  are  yet  affecting 
an  increase  in  temperature.  We  must  therefore  con- 
clude that  this  rise  in  the  isotherm  marking  glacial  ice 

*  Climatic  changes  indicated  by  Glaciers. 

Prof.  I.  C.  Russell,  Ain.  Geologist,  May,  1892,  vol.  ix,  No.  5.  In  ad- 
dition to  the  very  extensive  list  of  authorities  there  quoted  by  Prof. 
Russell,  see  also  Report  of  The  British  Ass'n.  1881,  p.  742. 

Life  of  Agassiz,  Vol.  II,  pp.  717  to  729  and  pp.  743  to  747. 

t  At  the  culmination  of  the  Ice  Age  evaporation  reached  its  minimum,  and 
hence  precipitation  was  also  at  a  minimum.  Since  that  Age  evaporation  has 
slowly  increased;  the  amount  of  moisture  in  the  atmosphere  being  depend- 
ant upon  its  temperature,  this  amount  has  also  increased.  The  aggregate 
amount  of  evaporation  and  the  aggregate  amount  of  precipitation  is 
slowly  increasing,  and  has  the  moderate  limit  fixed  by  natural  laws  for  in- 
crease of  mean  temperature.  Mars  appears  to  have  progressed  further  in 
this  mean  condition  than  the  earth.  The  smaller  mass  partly  accounts 
for  this. 


46 


is  due  primarily,  if  not  entirely,  to  an  accession  of  heat. 

It  has  been  demonstrated  that  at  the  culmination  of 
the  Ice  Age,  much  colder  conditions  existed  than  at 
present.  It  now  remains  to  explain  the  conditions  act- 
ing to  bring  about  existing  climates.  Upon  the  exhaus- 
tion of  the  last  available  remnant  of  earth  heat — left  in 
the  oceans  by  reason  of  the  high  specific  heat  of  water — 
the  supply  of  vapor  maintaining  the  cloud  envelop  was 
shut  off,  and  solar  heat  permitted  to  reach  the  planetary 
surface. 

That  direct  solar  rays  are  converted  into  obscure  or 
dark  heat  rays  by  contact  with  the  planetary  surface, 
and  that  the  atmosphere  of  our  planet  is  more  transca- 
lent to  the  former  than  to  the  latter,  has  been  fully 
demonstrated  by  Tyndall,*  although  slightly  modified 
by  Buff.f 

However  small  may  be  the  difference  between  the 
transcalency  of  the  atmosphere  to  direct  solar  rays  and 
to  the  dark  rays  into  which  the  direct  are  converted,  a 
gradual  rise  in  temperature  must  follow.  This  rise  must 
follow  wrhether  solar  energy  be  constant  or  slowly  de- 
creasing, the  rise  being  due  not  to  the  actual  amount  of 
heat  received,  but  to  the  difference  between  the  rate  of 
receipt  and  the  rate  of  loss. 

The  great  increase  of  mean  surface  temperatures  in 
equatorial,  temperate  and  sub-tropical  areas  being  due 
to  this  small  but  positive  difference  between  the  rates  of 
receipt  and  loss;  as  has  just  been  shown,  this  action  is 
yet  in  progress. 

These  deductions   are  radically  at  variance  with  the 

*  Archives  des  Sciences,  vol.  v,  p.  293.  Proc.  Koyal  Soc.,  vol.  xiii, 
p.  160. 

t  Archives  des  Sciences,  Berne,  vol.  Ivii,  p.  293,  et  seq. 


THEIR    CAUSES    AND    VARIATIONS.  47 

opinion  of  high  authorities  on  meteorology,  as  may  be 
seen  from  the  following  quotation:  "  It  is  evident  that 
our  planet,  considered  as  a  whole,  and  on  the  average  of 
many  years,  loses  all  the  heat  that  it  receives  from  the 
sun,  but  all  the  details  of  this  process  have  not  yet  been 
worked  out.*" 

The  author  is  unable  to  find  any  facts  to  sustain  this 
view^-all  tend  to  refute  it.  The  trapping  of  heat  by 
vapors  and  gases  of  the  atmosphere — the  gradual  retreat 
of  glaciers  in  both  hemispheres — and  the  vast  rise  in 
temperatures  since  the  culmination  of  the  Ice  Age — all 
conclusively  tend  to  corroborate  the  deductions  just 
reached — namely,  that  the  mean  surface  temperatures 
of  the  globe  have  been  and  are  yet  rising  from  the 
trapping  of  heat. 

It  does  not  follow  that  this  rise  has  an  indefinite  or 
excessive  limit,  as  the  oceans  become  warmer  they  are 
cooled  by  giving  off  more  vapor.  This  vapor,  when 
partly  condensed  into  clouds,  intercepts  solar  heat  in 
the  upper  atmosphere,  and  the  intense  white  of  the 
upper  surface  of  clouds  reflects  more  heat  into  space 
than  the  darker  planetary  surface  beneath  .^~ 

The  vast  store  of  cold  in  the  continental  ice  sheets 
has  been  greatly  exhausted;  there  yet  remains  the  vaster 
store  in  the  ice  cold  depths  of  the  oceans,  the  conserv- 
ative influence  of  which  cannot  be  estimated;  for  besides 
the  difficulties  of  heating  water  from  the  surface  down- 

*Dr.  Cleveland  Abbe,  U.  S.  Meteorological  Bureau.  Am.  Jour,  of 
Science,  May,  1892,  vol.  xliii,  p.  364. 

t  The  albedo  of  Jupiter  is  0.62;  that  of  Mars,  0.26,  of  the  moon  0.174. 
It  will  be  observed  that  the  planets  distinctly  shrouded  in  clouds  have 
high  reflective  powers;  those  planets  and  satellites  not  shrouded -have  very 
low  powers.  Venus,  in  this  respect,  seems  to  have  a  partially  obscured 
atmosphere,  her  albedo  being  0.50. 


48  GEOLOGICAL    AND    SOLAR    CLIMATES, 

wards,  there  yet  remains  the  cooling  effect  of  surface 
evaporation.  There  is  thus  presented  the  extreme  slow- 
ness of  the  methods  by  which  vast  changes  are  wrought. 
Here  are  agencies  whose  results  are  so  slight  as  not  to  be 
detected  by  thermometric  methods — yet  recording  their 
effects  in  grand  eras  of  climates  throughout  the  earth. 

The  planet  Mars  is  particularly  interesting,  having  a 
mass  less  than  one-ninth  (^T)  that  of  the  earth.  His 
loss  of  internal  heat  occurred  ages  before  that  of  the 
earth;  therefore,  Mars  has  been  a  heat-gathering  body 
longer  than  the  earth,  and  enjoys  a  milder  general  tem- 
perature,* although  that  planet  receives  less  than  half 
the  heat  and  light  received  by  the  earth  Jupiter  is  in 
a  condition  which  our  geological  history  proves  the  earth 
to  have  passed  through;  Mars  is  in  a  condition  towards 
which  the  earth  is  gradually  tending. f 

It  is  now  a  simple  matter  to  trace  the  steps  by  which 
glacial  conditions  were  removed  and  zones  of  climate 
established. 

Solar  energy  first  established  its  control  in  that  zone 
most  exposed  to  its  power — namely,  the  torrid  zone. 
From  this  zone  glacial  conditions  were  first  removed, 
and  this  removal  continued  north  and  south  upon  lines 
parallel  with  present  isotherms. 

In  considering  the  astronomical  causes,  and  the  phys- 
ical results  thereby  brought  about,  it  was  argued  that 
these  causes  tended  to  heat  the  northern  hemisphere 
more  rapidly  than  the  southern.  Dr.  Croll  and  other 
physicists,  have  so  fully  discussed  this  question  that  there 
remains  but  little  to.be  added. 

*  General  Astronomy.— Young;  p.  337. 

t  Venus  presents  a  condition  which  suggests  that  she  may  be  partly 
shrouded  in  clouds,  shutting  out  solar  heat,  just  as  the  thermal  equator 
of  the  earth  is  thus  partly  protected  by  the  equatorial  cloud  ring. 


THEIR    CAUSES    AND    VARIATIONS.  49 

The  prime  reason,  however,  seems  to  have  been 
omitted,  which  is  simply  this,  the  northern  hemisphere, 
containing  so  large  a  predominance  of  land  area,  was 
more  easily  warmed  than  the  southern.  This  unequal 
heating  once  inaugurated  would  establish  currents  both 
of  air  and  water  tending  to  perpetuate  this  action,  rein- 
forced as  it  is  by  geographical  and  cosmical  agencies. 

When,  by  this  gradual  accession  of  heat,  conditions 
and  temperatures  resembling  those  existing  prior  to  the 
Ice  Age,  were  re-established,  we  find  these  new  condi- 
tions restricted  to  latitudinal  belts  sensibly  parallel  with 
the  equator,  but  modified  by  elevation  and  ocean  cur- 
rents; whereas  the  corresponding  pre-glacial  climates 
were  independent  of  latitude. 

By  the  trapping  of  solar  heat  a  gradual  rise  in  tem- 
perature was  inaugurated  at  that  period,  when  by  the 
exhaustion  of  the  earth  heat,  left  in  the  oceans,  the 
enshrouding  clouds  were  removed.  Then,  and  not  until 
then,  do  we  find  the  removal  of  conditions  shutting  out 
solar  heat  written  in  zones  of  life  belting  the  earth.  In 
these  new  zones  of  climate  there  have  been  developed 
higher,  nobler  types  of  life,  and  with  the  birth  of  the 
seasons  there  was  ushered  in  upon  the  earth  that  Light 
which  is  developing  Psychozoic  Life. 


OJ  THE 

UHIVERSITT 


14  DAY  USE 

RETURN  TO  DESK  FROM  WHICH  BORROWED 

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MAYS    1961 

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*ec<o  ^ 

**n  ^ 

LD  21A-50m-12,'60 
(B6221slO)476B 


University  of  California 
Berkeley 


YC  67732 


